Search results

Title: Effect Of Coil Configuration Design On Al Solidified Structure Refinement.
Creator: Zhao, Jing, Yu, Ji-hao, Han, Ke, Zhong, Hong-gang, Li, Ren-xing, Zhai, Qi-jie
Abstract/Description: This paper outlines our effort to optimize PMO (Pulsed Magneto-Oscillation) design in order to improve the efficiency of ingot manufacturing. SPMO-H (Simplified Surface Pulse Magneto-Oscillation) and CPMO-H (Simplified Compound Pulse Magneto-Oscillation) were presented on the basis of SPMO (Surface Pulse Magneto-Oscillation) and CPMO (Compound Pulse Magneto-Oscillation). Our numerical and experimental results showed that optimized PMO coil design offered us a device that enabled the operator...
Show moreThis paper outlines our effort to optimize PMO (Pulsed Magneto-Oscillation) design in order to improve the efficiency of ingot manufacturing. SPMO-H (Simplified Surface Pulse Magneto-Oscillation) and CPMO-H (Simplified Compound Pulse Magneto-Oscillation) were presented on the basis of SPMO (Surface Pulse Magneto-Oscillation) and CPMO (Compound Pulse Magneto-Oscillation). Our numerical and experimental results showed that optimized PMO coil design offered us a device that enabled the operator to examine and operate the melt more convenient without losing the efficiency and decreasing refinement effect. Our work also showed the distance between the coil and the melt surface had little effect on the grain sizes refined. Therefore, in ingot production, the dropping of melt surface is not a problem for PMO application.
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Date Issued: 2020-01
Identifier: FSU_libsubv1_wos_000516827800152, 10.3390/met10010153
Format: Citation

Title: Relative Sorption Coefficient: Key To Tracing Petroleum Migration And Other Subsurface Fluids.
Creator: Zhang, L., Wang, Y., Li, M.-W., Yin, Q.-Z., Zhang, W.
Abstract/Description: The accumulation and spatial distribution of economically important petroleum in sedimentary basins are primarily controlled by its migration from source rocks through permeable carrier beds to reservoirs. Tracing petroleum migration entails the use of molecular indices established according to sorption capacities of polar molecules in migrating petroleum. However, little is known about molecular sorption capacities in natural migration systems, rendering these indices unreliable. Here, we...
Show moreThe accumulation and spatial distribution of economically important petroleum in sedimentary basins are primarily controlled by its migration from source rocks through permeable carrier beds to reservoirs. Tracing petroleum migration entails the use of molecular indices established according to sorption capacities of polar molecules in migrating petroleum. However, little is known about molecular sorption capacities in natural migration systems, rendering these indices unreliable. Here, we present a new approach based on a novel concept of relative sorption coefficient for quantitatively assessing sorption capacities of polar molecules during natural petroleum migration. Using this approach, we discovered previously unrecognized "stripping" and "impeding" effects that significantly reduce the sorption capacities of polar compounds. These discoveries provide new insights into the behaviors of polar compounds and can easily explain why traditional molecular indices yield incorrect information about petroleum migration. In light of these new findings, we established new molecular indices for tracing petroleum migration. We demonstrate via case studies that the newly established indices, unlike traditional molecular indices, are reliable and effective in tracing petroleum migration. Our approach can be applied to diverse basins around the world to reveal distribution patterns of petroleum, which would decrease environmental risks of exploration by reducing unsuccessful wells.
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Date Issued: 2019-11-14
Identifier: FSU_libsubv1_wos_000496416000055, 10.1038/s41598-019-52259-6
Format: Citation

Title: Classification Of Plasma Cell Disorders By 21 Tesla Fourier Transform Ion Cyclotron Resonance Top-down And Middle-down Ms/ms Analysis Of Monoclonal Immunoglobulin Light Chains In Human Serum.
Creator: He, Lidong, Anderson, Lissa C., Barnidge, David R., Murray, David L., Dasari, Surendra, Dispenzieri, Angela, Hendrickson, Christopher L., Marshall, Alan G.
Abstract/Description: The current five-year survival rate for systemic AL amyloidosis or multiple myeloma is 51%, indicating the urgent need for better diagnosis methods and treatment plans. Here, we describe highly specific and sensitive top-down and middle-down MS/MS methods owning the advantages of fast sample preparation, ultrahigh mass accuracy, and extensive residue cleavages with 21 telsa FT-ICR MS/MS. Unlike genomic testing, which requires bone marrow aspiration and may fail to identify all monoclonal...
Show moreThe current five-year survival rate for systemic AL amyloidosis or multiple myeloma is 51%, indicating the urgent need for better diagnosis methods and treatment plans. Here, we describe highly specific and sensitive top-down and middle-down MS/MS methods owning the advantages of fast sample preparation, ultrahigh mass accuracy, and extensive residue cleavages with 21 telsa FT-ICR MS/MS. Unlike genomic testing, which requires bone marrow aspiration and may fail to identify all monoclonal immunoglobulins produced by the body, the present method requires only a blood draw. In addition, circulating monoclonal immunoglobulins spanning the entire population are analyzed and reflect the selection of germline sequence by B cells. The monoclonal immunoglobulin light chain FR2-CDR2-FR3 was sequenced by database-aided de novo MS/MS and 100% matched the gene sequencing result, except for two amino acids with isomeric counterparts, enabling accurate germline sequence classification. The monoclonal immunoglobulin heavy chains were also classified into specific germline sequences based on the present method. This work represents the first application of top/middle-down MS/MS sequencing of endogenous human monoclonal immunoglobulins with polyclonal immunoglobulins background.
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Date Issued: 2019-03-05
Identifier: FSU_libsubv1_wos_000460709200015, 10.1021/acs.analchem.8b03294
Format: Citation

Title: Control Of Hexamerization, Assembly, And Excluded Strand Specificity For The Sulfolobus Solfataricus Mcm Helicase.
Creator: Graham, Brian W., Bougoulias, Michael E., Dodge, Katie L., Thaxton, Carly T., Olaso, Danae, Tao, Yeqing, Young, Nicolas L., Marshall, Alan G., Trakselis, Michael A.
Abstract/Description: A growing body of evidence supports a steric exclusion and wrapping model for DNA unwinding in which hexameric helicases interact with the excluded single-stranded DNA (ssDNA) in addition to the encircled strand. Interactions with the excluded ssDNA have been shown to be mediated primarily by electrostatic interactions, but base stacking with surface-exposed tyrosine residues is an alternative hypothesis. Here, we mutated several external tyrosine and positively charged residues from full...
Show moreA growing body of evidence supports a steric exclusion and wrapping model for DNA unwinding in which hexameric helicases interact with the excluded single-stranded DNA (ssDNA) in addition to the encircled strand. Interactions with the excluded ssDNA have been shown to be mediated primarily by electrostatic interactions, but base stacking with surface-exposed tyrosine residues is an alternative hypothesis. Here, we mutated several external tyrosine and positively charged residues from full-length Sulfolobus solfataricus MCM along the proposed path of excluded strand binding and assessed their impact on DNA unwinding. Four of the five tyrosine residues had significant decreases in their level of unwinding, and one, Y519A, located within the alpha/beta-alpha linker region of the C-terminal domain, had the most severe perturbation attributed to the disruption of hexamerization. The Y519 mutant exhibits an enhanced and stabilized secondary structure that is modulated by temperature, binding DNA with a higher apparent affinity and suggesting a pathway for hexameric assembly. Hydrogen/deuterium exchange coupled to mass spectrometry was used to map deuterium uptake differences between wild-type and Y519A apo structures highlighting global differences in solvent accessible areas consistent with altered quaternary structure. Two of the five electrostatic mutants had significantly reduced levels of DNA unwinding and combined with previous mutations better define the exterior binding path. The importance of the electrostatic excluded strand interaction was confirmed by use of morpholino DNA substrates that showed analogous reduced unwinding rates. These results better define the hexameric assembly and influence of the excluded strand interactions in controlling DNA unwinding by the archaeal MCM complex.
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Date Issued: 2018-10-02
Identifier: FSU_libsubv1_wos_000446542800005, 10.1021/acs.biochem.8b00766
Format: Citation

Title: Symmetry, Maximally Localized Wannier States, And A Low-energy Model For Twisted Bilayer Graphene Narrow Bands.
Creator: Kang, Jian, Vafek, Oskar
Abstract/Description: We build symmetry-adapted maximally localized Wannier states and construct the low-energy tight-binding model for the four narrow bands of twisted bilayer graphene. We do so when the twist angle is commensurate near the "magic" value and the narrow bands are separated from the rest of the bands by energy gaps. On each layer and sublattice, every Wannier state has three peaks near the triangular moire lattice sites. However, each Wannier state is localized and centered around a site of the...
Show moreWe build symmetry-adapted maximally localized Wannier states and construct the low-energy tight-binding model for the four narrow bands of twisted bilayer graphene. We do so when the twist angle is commensurate near the "magic" value and the narrow bands are separated from the rest of the bands by energy gaps. On each layer and sublattice, every Wannier state has three peaks near the triangular moire lattice sites. However, each Wannier state is localized and centered around a site of the honeycomb lattice that is dual to the triangular moire lattice. The space group and the time-reversal symmetries are realized locally. The corresponding tight-binding model provides a starting point for studying the correlated many-body phases.
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Date Issued: 2018-09-28
Identifier: FSU_libsubv1_wos_000446282000002, 10.1103/PhysRevX.8.031088
Format: Citation

Title: Resonant Torsion Magnetometry In Anisotropic Quantum Materials.
Creator: Modic, K. A., Bachmann, Maja D., Ramshaw, B. J., Arnold, F., Shirer, K. R., Estry, Amelia, Betts, J. B., Ghimire, Nirmal J., Bauer, E. D., Schmidt, Marcus, Baenitz, Michael,...
Show moreModic, K. A., Bachmann, Maja D., Ramshaw, B. J., Arnold, F., Shirer, K. R., Estry, Amelia, Betts, J. B., Ghimire, Nirmal J., Bauer, E. D., Schmidt, Marcus, Baenitz, Michael, Svanidze, E., McDonald, Ross D., Shekhter, Arkady, Moll, Philip J. W.
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Abstract/Description: Unusual behavior in quantum materials commonly arises from their effective low-dimensional physics, reflecting the underlying anisotropy in the spin and charge degrees of freedom. Here we introduce the magnetotropic coefficient k = partial derivative F-2/partial derivative theta(2), the second derivative of the free energy F with respect to the magnetic field orientation theta in the crystal. We show that the magnetotropic coefficient can be quantitatively determined from a shift in the...
Show moreUnusual behavior in quantum materials commonly arises from their effective low-dimensional physics, reflecting the underlying anisotropy in the spin and charge degrees of freedom. Here we introduce the magnetotropic coefficient k = partial derivative F-2/partial derivative theta(2), the second derivative of the free energy F with respect to the magnetic field orientation theta in the crystal. We show that the magnetotropic coefficient can be quantitatively determined from a shift in the resonant frequency of a commercially available atomic force microscopy cantilever under magnetic field. This detection method enables part per 100 million sensitivity and the ability to measure magnetic anisotropy in nanogram-scale samples, as demonstrated on the Weyl semimetal NbP. Measurement of the magnetotropic coefficient in the spin-liquid candidate RuCl3 highlights its sensitivity to anisotropic phase transitions and allows a quantitative comparison to other thermodynamic coefficients via the Ehrenfest relations.
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Date Issued: 2018-09-28
Identifier: FSU_libsubv1_wos_000445886000001, 10.1038/s41467-018-06412-w
Format: Citation

Title: Quantum Anomalous Hall Insulator Stabilized By Competing Interactions.
Creator: Sur, Shouvik, Gong, Shou-Shu, Yang, Kun, Vafek, Oskar
Abstract/Description: We study the quantum phases driven by interaction in a semimetal with a quadratic band touching at the Fermi level. By combining the density matrix renormalization group (DMRG), analytical power expanded Gibbs potential method, and the weak coupling renormalization group, we study a spinless fermion system on a checkerboard lattice at half-filling, which has a quadratic band touching in the absence of interaction. In the presence of strong nearest-neighbor (V-1) and next-nearest-neighbor (V-2...
Show moreWe study the quantum phases driven by interaction in a semimetal with a quadratic band touching at the Fermi level. By combining the density matrix renormalization group (DMRG), analytical power expanded Gibbs potential method, and the weak coupling renormalization group, we study a spinless fermion system on a checkerboard lattice at half-filling, which has a quadratic band touching in the absence of interaction. In the presence of strong nearest-neighbor (V-1) and next-nearest-neighbor (V-2) interactions, we identify a site nematic insulator phase, a stripe insulator phase, and a phase separation region, in agreement with the phase diagram obtained analytically in the strong coupling limit (i.e., in the absence of fermion hopping). In the intermediate interaction regime we establish a quantum anomalous Hall phase in the DMRG as evidenced by the spontaneous time-reversal symmetry breaking and the appearance of a quantized Chern number C = 1. For weak interaction we utilize the power expanded Gibbs potential method that treats V-1 and V-2 on equal footing, as well as the weak coupling renormalization group. Our analytical results reveal that not only the repulsive V-1 interaction, but also the V-2 interaction (both repulsive and attractive), can drive the quantum anomalous Hall phase. We also determine the phase boundary in the V-1-V-2 plane that separates the semimetal from the quantum anomalous Hall state. Finally, we show that the nematic semimetal, which was proposed for vertical bar V-2 vertical bar >> V-1 at weak coupling in a previous study, is absent, and the quantum anomalous Hall state is the only weak coupling instability of the spinless quadratic band touching semimetal.
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Date Issued: 2018-09-26
Identifier: FSU_libsubv1_wos_000445726500005, 10.1103/PhysRevB.98.125144
Format: Citation

Title: Observation Of Cyclotron Antiresonance In The Topological Insulator Bi2te3.
Creator: Dordevic, S., Lei, Hechang, Petrovic, C., Ludwig, J., Li, Z. Q., Smirnov, D.
Abstract/Description: We report on the experimental observation of a cyclotron antiresonance in a canonical three-dimensional topological insulator Bi2Te3. Magnetoreflectance response of single-crystal Bi2Te3 was studied in 18-T magnetic field, and compared to other topological insulators studied before, the main spectral feature is inverted. We refer to it as an antiresonance. In order to describe this unconventional behavior we propose the idea of an imaginary cyclotron resonance frequency, which on the other...
Show moreWe report on the experimental observation of a cyclotron antiresonance in a canonical three-dimensional topological insulator Bi2Te3. Magnetoreflectance response of single-crystal Bi2Te3 was studied in 18-T magnetic field, and compared to other topological insulators studied before, the main spectral feature is inverted. We refer to it as an antiresonance. In order to describe this unconventional behavior we propose the idea of an imaginary cyclotron resonance frequency, which on the other hand indicates that the form of the Lorentz force that magnetic field exerts on charge carriers takes an unconventional form.
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Date Issued: 2018-09-20
Identifier: FSU_libsubv1_wos_000445173200003, 10.1103/PhysRevB.98.115138
Format: Citation

Title: Biexcitons In Monolayer Transition Metal Dichalcogenides Tuned By Magnetic Fields.
Creator: Stevens, Christopher E., Paul, Jagannath, Cox, Timothy, Sahoo, Prasana K., Gutierrez, Humberto R., Turkowski, Volodymyr, Semenov, Dimitry, McGill, Steven A., Kapetanakis, Myron...
Show moreStevens, Christopher E., Paul, Jagannath, Cox, Timothy, Sahoo, Prasana K., Gutierrez, Humberto R., Turkowski, Volodymyr, Semenov, Dimitry, McGill, Steven A., Kapetanakis, Myron D., Perakis, Ilias E., Hilton, David J., Karaiskaj, Denis
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Abstract/Description: We present time-integrated four-wave mixing measurements on monolayer MoSe2 in magnetic fields up to 25 T. The experimental data together with time-dependent density function theory calculations provide interesting insights into the biexciton formation and dynamics. In the presence of magnetic fields the coherence at negative and positive time delays is dominated by intervalley biexcitons. We demonstrate that magnetic fields can serve as a control to enhance the biexciton formation and help...
Show moreWe present time-integrated four-wave mixing measurements on monolayer MoSe2 in magnetic fields up to 25 T. The experimental data together with time-dependent density function theory calculations provide interesting insights into the biexciton formation and dynamics. In the presence of magnetic fields the coherence at negative and positive time delays is dominated by intervalley biexcitons. We demonstrate that magnetic fields can serve as a control to enhance the biexciton formation and help search for more exotic states of matter, including the creation of multiple exciton complexes and excitonic condensates.
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Date Issued: 2018-09-13
Identifier: FSU_libsubv1_wos_000444494800004, 10.1038/s41467-018-05643-1
Format: Citation

Title: Efficient Generation Of Neutral And Charged Biexcitons In Encapsulated Wse2 Monolayers.
Creator: Ye, Ziliang, Waldecker, Lutz, Ma, Eric Yue, Rhodes, Daniel, Antony, Abhinandan, Kim, Bumho, Zhang, Xiao-Xiao, Deng, Minda, Jiang, Yuxuan, Lu, Zhengguang, Smirnov, Dmitry,...
Show moreYe, Ziliang, Waldecker, Lutz, Ma, Eric Yue, Rhodes, Daniel, Antony, Abhinandan, Kim, Bumho, Zhang, Xiao-Xiao, Deng, Minda, Jiang, Yuxuan, Lu, Zhengguang, Smirnov, Dmitry, Watanabe, Kenji, Taniguchi, Takashi, Hone, James, Heinz, Tony F.
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Abstract/Description: Higher-order correlated excitonic states arise from the mutual interactions of excitons, which generally requires a significant exciton density and therefore high excitation levels. Here, we report the emergence of two biexcitons species, one neutral and one charged, in monolayer tungsten diselenide under moderate continuous-wave excitation. The efficient formation of biexcitons is facilitated by the long lifetime of the dark exciton state associated with a spin-forbidden transition, as well...
Show moreHigher-order correlated excitonic states arise from the mutual interactions of excitons, which generally requires a significant exciton density and therefore high excitation levels. Here, we report the emergence of two biexcitons species, one neutral and one charged, in monolayer tungsten diselenide under moderate continuous-wave excitation. The efficient formation of biexcitons is facilitated by the long lifetime of the dark exciton state associated with a spin-forbidden transition, as well as improved sample quality from encapsulation between hexagonal boron nitride layers. From studies of the polarization and magnetic field dependence of the neutral biexciton, we conclude that this species is composed of a bright and a dark excitons residing in opposite valleys in momentum space. Our observations demonstrate that the distinctive features associated with biexciton states can be accessed at low light intensities and excitation densities.
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Date Issued: 2018-09-13
Identifier: FSU_libsubv1_wos_000444494800002, 10.1038/s41467-018-05917-8
Format: Citation

Title: Revealing The Biexciton And Trion-exciton Complexes In Bn Encapsulated Wse2.
Creator: Li, Zhipeng, Wang, Tianmeng, Lu, Zhengguang, Jin, Chenhao, Chen, Yanwen, Meng, Yuze, Lian, Zhen, Taniguchi, Takashi, Watanabe, Kenji, Zhang, Shengbai, Smirnov, Dmitry, Shi, Su-Fei
Abstract/Description: Strong Coulomb interactions in single-layer transition metal dichalcogenides (TMDs) result in the emergence of strongly bound excitons, trions, and biexcitons. These excitonic complexes possess the valley degree of freedom, which can be exploited for quantum optoelectronics. However, in contrast to the good understanding of the exciton and trion properties, the binding energy of the biexciton remains elusive, with theoretical calculations and experimental studies reporting discrepant results....
Show moreStrong Coulomb interactions in single-layer transition metal dichalcogenides (TMDs) result in the emergence of strongly bound excitons, trions, and biexcitons. These excitonic complexes possess the valley degree of freedom, which can be exploited for quantum optoelectronics. However, in contrast to the good understanding of the exciton and trion properties, the binding energy of the biexciton remains elusive, with theoretical calculations and experimental studies reporting discrepant results. In this work, we resolve the conflict by employing low-temperature photoluminescence spectroscopy to identify the biexciton state in BN-encapsulated single-layer WSe2. The biexciton state only exists in charge-neutral WSe2, which is realized through the control of efficient electrostatic gating. In the lightly electron-doped WSe2, one free electron binds to a biexciton and forms the trion-exciton complex. Improved understanding of the biexciton and trion-exciton complexes paves the way for exploiting the many-body physics in TMDs for novel optoelectronics applications.
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Date Issued: 2018-09-13
Identifier: FSU_libsubv1_wos_000444494800003, 10.1038/s41467-018-05863-5
Format: Citation

Title: Efficient generation of neutral and charged biexcitons in encapsulated WSe monolayers.
Creator: Ye, Ziliang, Waldecker, Lutz, Ma, Eric Yue, Rhodes, Daniel, Antony, Abhinandan, Kim, Bumho, Zhang, Xiao-Xiao, Deng, Minda, Jiang, Yuxuan, Lu, Zhengguang, Smirnov, Dmitry,...
Show moreYe, Ziliang, Waldecker, Lutz, Ma, Eric Yue, Rhodes, Daniel, Antony, Abhinandan, Kim, Bumho, Zhang, Xiao-Xiao, Deng, Minda, Jiang, Yuxuan, Lu, Zhengguang, Smirnov, Dmitry, Watanabe, Kenji, Taniguchi, Takashi, Hone, James, Heinz, Tony F
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Abstract/Description: Higher-order correlated excitonic states arise from the mutual interactions of excitons, which generally requires a significant exciton density and therefore high excitation levels. Here, we report the emergence of two biexcitons species, one neutral and one charged, in monolayer tungsten diselenide under moderate continuous-wave excitation. The efficient formation of biexcitons is facilitated by the long lifetime of the dark exciton state associated with a spin-forbidden transition, as well...
Show moreHigher-order correlated excitonic states arise from the mutual interactions of excitons, which generally requires a significant exciton density and therefore high excitation levels. Here, we report the emergence of two biexcitons species, one neutral and one charged, in monolayer tungsten diselenide under moderate continuous-wave excitation. The efficient formation of biexcitons is facilitated by the long lifetime of the dark exciton state associated with a spin-forbidden transition, as well as improved sample quality from encapsulation between hexagonal boron nitride layers. From studies of the polarization and magnetic field dependence of the neutral biexciton, we conclude that this species is composed of a bright and a dark excitons residing in opposite valleys in momentum space. Our observations demonstrate that the distinctive features associated with biexciton states can be accessed at low light intensities and excitation densities.
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Date Issued: 2018-09-13
Identifier: FSU_pmch_30214026, 10.1038/s41467-018-05917-8, PMC6137141, 30214026, 30214026, 10.1038/s41467-018-05917-8
Format: Citation

Title: Biexcitons in monolayer transition metal dichalcogenides tuned by magnetic fields.
Creator: Stevens, Christopher E, Paul, Jagannath, Cox, Timothy, Sahoo, Prasana K, Gutiérrez, Humberto R, Turkowski, Volodymyr, Semenov, Dimitry, McGill, Steven A, Kapetanakis, Myron D,...
Show moreStevens, Christopher E, Paul, Jagannath, Cox, Timothy, Sahoo, Prasana K, Gutiérrez, Humberto R, Turkowski, Volodymyr, Semenov, Dimitry, McGill, Steven A, Kapetanakis, Myron D, Perakis, Ilias E, Hilton, David J, Karaiskaj, Denis
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Abstract/Description: We present time-integrated four-wave mixing measurements on monolayer MoSe in magnetic fields up to 25 T. The experimental data together with time-dependent density function theory calculations provide interesting insights into the biexciton formation and dynamics. In the presence of magnetic fields the coherence at negative and positive time delays is dominated by intervalley biexcitons. We demonstrate that magnetic fields can serve as a control to enhance the biexciton formation and help...
Show moreWe present time-integrated four-wave mixing measurements on monolayer MoSe in magnetic fields up to 25 T. The experimental data together with time-dependent density function theory calculations provide interesting insights into the biexciton formation and dynamics. In the presence of magnetic fields the coherence at negative and positive time delays is dominated by intervalley biexcitons. We demonstrate that magnetic fields can serve as a control to enhance the biexciton formation and help search for more exotic states of matter, including the creation of multiple exciton complexes and excitonic condensates.
Show less
Date Issued: 2018-09-13
Identifier: FSU_pmch_30213976, 10.1038/s41467-018-05643-1, PMC6137096, 30213976, 30213976, 10.1038/s41467-018-05643-1
Format: Citation

Title: Giant Pressure Dependence And Dimensionality Switching In A Metal-organic Quantum Antiferromagnet.
Creator: Wehinger, B., Fiolka, C., Lanza, A., Scatena, R., Kubus, M., Grockowiak, A., Coniglio, W. A., Graf, D., Skoulatos, M., Chen, J.-H., Gukelberger, J., Casati, N., Zaharko, O.,...
Show moreWehinger, B., Fiolka, C., Lanza, A., Scatena, R., Kubus, M., Grockowiak, A., Coniglio, W. A., Graf, D., Skoulatos, M., Chen, J.-H., Gukelberger, J., Casati, N., Zaharko, O., Macchi, P., Kramer, K. W., Tozer, S., Mudry, C., Normand, B., Ruegg, Ch
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Abstract/Description: We report an extraordinary pressure dependence of the magnetic interactions in the metal-organic system [CuF2(H2O)(2)](2) pyrazine. At zero pressure, this material realizes a quasi-two-dimensional spin-1/2 squarelattice Heisenberg antiferromagnet. By high-pressure, high-field susceptibility measurements we show that the dominant exchange parameter is reduced continuously by a factor of 2 on compression. Above 18 kbar, a phase transition occurs, inducing an orbital re-ordering that switches...
Show moreWe report an extraordinary pressure dependence of the magnetic interactions in the metal-organic system [CuF2(H2O)(2)](2) pyrazine. At zero pressure, this material realizes a quasi-two-dimensional spin-1/2 squarelattice Heisenberg antiferromagnet. By high-pressure, high-field susceptibility measurements we show that the dominant exchange parameter is reduced continuously by a factor of 2 on compression. Above 18 kbar, a phase transition occurs, inducing an orbital re-ordering that switches the dimensionality, transforming the quasi-two-dimensional lattice into weakly coupled chains. We explain the microscopic mechanisms for both phenomena by combining detailed x-ray and neutron diffraction studies with quantitative modeling using spin-polarized density functional theory.
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Date Issued: 2018-09-11
Identifier: FSU_libsubv1_wos_000444586600017, 10.1103/PhysRevLett.121.117201
Format: Citation

Title: Dipolar-octupolar Ising Antiferromagnetism In Sm2ti2o7: A Moment Fragmentation Candidate.
Creator: Mauws, C., Hallas, A. M., Sala, G., Aczel, A. A., Sarte, P. M., Gaudet, J., Ziat, D., Quilliam, J. A., Lussier, J. A., Bieringer, M., Zhou, H. D., Wildes, A., Stone, I. M. B.,...
Show moreMauws, C., Hallas, A. M., Sala, G., Aczel, A. A., Sarte, P. M., Gaudet, J., Ziat, D., Quilliam, J. A., Lussier, J. A., Bieringer, M., Zhou, H. D., Wildes, A., Stone, I. M. B., Abernathy, D., Luke, G. M., Gaulin, B. D., Wiebe, C. R.
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Abstract/Description: Over the past two decades, the magnetic ground states of all rare-earth titanate pyrochlores have been extensively studied, with the exception of Sm2Ti2O7. This is, in large part, due to the very high absorption cross section of naturally occurring samarium, which renders neutron scattering infeasible. To combat this, we have grown a large, isotopically enriched single crystal of Sm2Ti2O7. Using inelastic neutron scattering, we determine that the crystal field ground state for Sm3+ is a...
Show moreOver the past two decades, the magnetic ground states of all rare-earth titanate pyrochlores have been extensively studied, with the exception of Sm2Ti2O7. This is, in large part, due to the very high absorption cross section of naturally occurring samarium, which renders neutron scattering infeasible. To combat this, we have grown a large, isotopically enriched single crystal of Sm2Ti2O7. Using inelastic neutron scattering, we determine that the crystal field ground state for Sm3+ is a dipolar-octupolar doublet with Ising anisotropy. Neutron diffraction experiments reveal that Sm2Ti2O7 orders into the all-in, all-out magnetic structure with an ordered moment of 0.44(7)mu(B) below T-N = 0.35 K, consistent with expectations for antiferromagnetically coupled Ising spins on the pyrochlore lattice. Zero-field muon spin relaxation measurements reveal an absence of spontaneous oscillations and persistent spin fluctuations down to 0.03 K. The combination of the dipolar-octupolar nature of the Sm3+ moment, the all-in, all-out ordered state, and the low-temperature persistent spin dynamics make this material an intriguing candidate for moment fragmentation physics.
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Date Issued: 2018-09-05
Identifier: FSU_libsubv1_wos_000443672100001, 10.1103/PhysRevB.98.100401
Format: Citation

Title: Intermittency Enhancement In Quantum Turbulence In Superfluid He-4.
Creator: Varga, Emil, Gao, Jian, Guo, Wei, Skrbek, Ladislav
Abstract/Description: Intermittency is a hallmark of turbulence, which exists not only in turbulent flows of classical viscous fluids but also in flows of quantum fluids such as superfluid He-4. Despite the established similarity between turbulence in classical fluids and quasiclassical turbulence in superfluid He-4, it has been predicted that intermittency in superfluid He-4 is temperature dependent and enhanced for certain temperatures, which is in striking contrasts to the nearly flow-independent intermittency...
Show moreIntermittency is a hallmark of turbulence, which exists not only in turbulent flows of classical viscous fluids but also in flows of quantum fluids such as superfluid He-4. Despite the established similarity between turbulence in classical fluids and quasiclassical turbulence in superfluid He-4, it has been predicted that intermittency in superfluid He-4 is temperature dependent and enhanced for certain temperatures, which is in striking contrasts to the nearly flow-independent intermittency in classical turbulence. Experimental verification of this theoretical prediction is challenging since it requires well-controlled generation of quantum turbulence in He-4 and flow measurement tools with high spatial and temporal resolution. Here we report an experimental study of quantum turbulence generated by towing a grid through a stationary sample of superfluid He-4. The decaying turbulent quantum flow is probed by combining a recently developed He*(2) molecular tracer-line tagging velocimetry technique and a traditional second-sound attenuation method. We observe quasiclassical decays of turbulent kinetic energy in the normal fluid and of vortex line density in the superfluid component. For several time instants during the decay, we calculate the transverse velocity structure functions. Their scaling exponents, deduced using the extended self-similarity hypothesis, display nonmonotonic temperature-dependent intermittency enhancement, in excellent agreement with a recent theoretical and numerical study
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Date Issued: 2018-09-04
Identifier: FSU_libsubv1_wos_000443685600007, 10.1103/PhysRevFluids.3.094601
Format: Citation

Title: Lipid Extraction by α-Synuclein Generates Semi-Transmembrane Defects and Lipoprotein Nanoparticles.
Creator: Pan, Jianjun, Dalzini, Annalisa, Khadka, Nawal K, Aryal, Chinta M, Song, Likai
Abstract/Description: Modulations of synaptic membranes play an essential role in the physiological and pathological functions of the presynaptic protein α-synuclein (αSyn). Here we used solution atomic force microscopy (AFM) and electron paramagnetic resonance (EPR) spectroscopy to investigate membrane modulations caused by αSyn. We used several lipid bilayers to explore how different lipid species may regulate αSyn-membrane interactions. We found that at a protein-to-lipid ratio of ∼1/9, αSyn perturbed lipid...
Show moreModulations of synaptic membranes play an essential role in the physiological and pathological functions of the presynaptic protein α-synuclein (αSyn). Here we used solution atomic force microscopy (AFM) and electron paramagnetic resonance (EPR) spectroscopy to investigate membrane modulations caused by αSyn. We used several lipid bilayers to explore how different lipid species may regulate αSyn-membrane interactions. We found that at a protein-to-lipid ratio of ∼1/9, αSyn perturbed lipid bilayers by generating semi-transmembrane defects that only span one leaflet. In addition, αSyn coaggregates with lipid molecules to produce ∼10 nm-sized lipoprotein nanoparticles. The obtained AFM data are consistent with the apolipoprotein characteristic of αSyn. The role of anionic lipids was elucidated by comparing results from zwitterionic and anionic lipid bilayers. Specifically, our AFM measurements showed that anionic bilayers had a larger tendency of forming bilayer defects; similarly, our EPR measurements revealed that anionic bilayers exhibited more substantial changes in lipid chain mobility and bilayer polarity. We also studied the effect of cholesterol. We found that cholesterol increased the capability of αSyn in inducing bilayer defects and altering lipid chain mobility and bilayer polarity. These data can be explained by an increase in the lipid headgroup-headgroup spacing and/or specific cholesterol-αSyn interactions. Interestingly, we found an inhibitory effect of the cone-shaped phosphatidylethanolamine lipids on αSyn-induced bilayer remodeling. We explained our data by considering interlipid hydrogen-bonding that can stabilize bilayer organization and suppress lipid extraction. Our results of lipid-dependent membrane modulations are likely relevant to αSyn functioning.
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Date Issued: 2018-08-31
Identifier: FSU_pmch_30198000, 10.1021/acsomega.8b01462, PMC6120733, 30198000, 30198000
Format: Citation

Title: Sensitivity Of T-c To Pressure And Magnetic Field In The Cuprate Superconductor Yba2cu3oy: Evidence Of Charge-order Suppression By Pressure.
Creator: Cyr-Choiniere, O., LeBoeuf, D., Badoux, S., Dufour-Beausejour, S., Bonn, D. A., Hardy, W. N., Liang, R., Graf, D., Doiron-Leyraud, N., Taillefer, Louis
Abstract/Description: Cuprate superconductors have a universal tendency to form charge density-wave (CDW) order which competes with superconductivity and is strongest at a doping p similar or equal to 0.12. Here we show that in the archetypal cuprate YBa2Cu3Oy (YBCO) pressure suppresses charge order but does not affect the pseudogap phase. This is based on transport measurements under pressure, which reveal that the onset of the pseudogap at T* is independent of pressure, while the negative Hall effect, a clear...
Show moreCuprate superconductors have a universal tendency to form charge density-wave (CDW) order which competes with superconductivity and is strongest at a doping p similar or equal to 0.12. Here we show that in the archetypal cuprate YBa2Cu3Oy (YBCO) pressure suppresses charge order but does not affect the pseudogap phase. This is based on transport measurements under pressure, which reveal that the onset of the pseudogap at T* is independent of pressure, while the negative Hall effect, a clear signature of CDW order in YBCO, is suppressed by pressure. We also find that pressure and magnetic field shift the superconducting transition temperature T-c of YBCO in the same way as a function of doping-but in opposite directions-and most effectively at p similar or equal to 0.12. This shows that the competition between superconductivity and CDW order can be tuned in two ways, either by suppressing superconductivity with field or suppressing CDW order by pressure. Based on existing high-pressure data and our own work, we observe that when CDW order is fully suppressed at high pressure, the so-called "1/8 anomaly" in the superconducting dome vanishes, revealing a smooth T-c dome which now peaks at p similar or equal to 0.13. We propose that this T-c dome is shaped by the competing effects of the pseudogap phase below its critical point p* similar to 0.19 and spin order at low doping.
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Date Issued: 2018-08-30
Identifier: FSU_libsubv1_wos_000443139600006, 10.1103/PhysRevB.98.064513
Format: Citation

Title: Precipitous Change Of The Irreversible Strain Limit With Heat-treatment Temperature In Nb3sn Wires Made By The Restacked-rod Process.
Creator: Cheggour, Najib, Stauffer, Theodore C., Starch, William, Lee, Peter J., Splett, Jolene D., Goodrich, Loren F., Ghosh, Arup K.
Abstract/Description: The intrinsic irreversible strain limit epsilon(irr,0) of Nb3Sn superconducting wires, made by the restacked-rod process and doped with either Ti or Ta, undergoes a precipitous change as a function of temperature. of the final heat-treatment for forming the A15 phase. Nb3Sn transitions from a highly brittle state where it cracks as soon as it is subjected to an axial tensile strain of any measurable amount, to a state more resilient to tensile strain as high as 0.4%. The remarkable abruptness...
Show moreThe intrinsic irreversible strain limit epsilon(irr,0) of Nb3Sn superconducting wires, made by the restacked-rod process and doped with either Ti or Ta, undergoes a precipitous change as a function of temperature. of the final heat-treatment for forming the A15 phase. Nb3Sn transitions from a highly brittle state where it cracks as soon as it is subjected to an axial tensile strain of any measurable amount, to a state more resilient to tensile strain as high as 0.4%. The remarkable abruptness of this transition (as most of it occurs over a range of only 10 degrees C) could pose real challenges for the heat-treatment of large magnets, such as those fabricated for the high-luminosity upgrade of the Large Hadron Collider (LHC). We named this behavior the strain irreversibility cliff (SIC) to caution magnet developers. The approach to fulfilling application requirements just in terms of the conductor's residual resistivity ratio RRR and critical-current density J(c) is incomplete. Along with RRR and J(c) wire specifications, and sub-element size requirements that reduce wire magnetization and instabilities effects, SIC imposes additional constraints on the choice of heat-treatment conditions to ensure mechanical integrity of the conductor.
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Date Issued: 2018-08-29
Identifier: FSU_libsubv1_wos_000443004500004, 10.1038/s41598-018-30911-x
Format: Citation

Title: Precipitous change of the irreversible strain limit with heat-treatment temperature in NbSn wires made by the restacked-rod process.
Creator: Cheggour, Najib, Stauffer, Theodore C, Starch, William, Lee, Peter J, Splett, Jolene D, Goodrich, Loren F, Ghosh, Arup K
Abstract/Description: The intrinsic irreversible strain limit ε of NbSn superconducting wires, made by the restacked-rod process and doped with either Ti or Ta, undergoes a precipitous change as a function of temperature θ of the final heat-treatment for forming the A15 phase. NbSn transitions from a highly brittle state where it cracks as soon as it is subjected to an axial tensile strain of any measurable amount, to a state more resilient to tensile strain as high as 0.4%. The remarkable abruptness of this...
Show moreThe intrinsic irreversible strain limit ε of NbSn superconducting wires, made by the restacked-rod process and doped with either Ti or Ta, undergoes a precipitous change as a function of temperature θ of the final heat-treatment for forming the A15 phase. NbSn transitions from a highly brittle state where it cracks as soon as it is subjected to an axial tensile strain of any measurable amount, to a state more resilient to tensile strain as high as 0.4%. The remarkable abruptness of this transition (as most of it occurs over a range of only 10 °C) could pose real challenges for the heat-treatment of large magnets, such as those fabricated for the high-luminosity upgrade of the Large Hadron Collider (LHC). We named this behavior the strain irreversibility cliff (SIC) to caution magnet developers. The approach to fulfilling application requirements just in terms of the conductor's residual resistivity ratio RRR and critical-current density J is incomplete. Along with RRR and J wire specifications, and sub-element size requirements that reduce wire magnetization and instabilities effects, SIC imposes additional constraints on the choice of heat-treatment conditions to ensure mechanical integrity of the conductor.
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Date Issued: 2018-08-29
Identifier: FSU_pmch_30158591, 10.1038/s41598-018-30911-x, PMC6115397, 30158591, 30158591, 10.1038/s41598-018-30911-x
Format: Citation

Title: Phase Modulators Based On High Mobility Ambipolar Rese2 Field-effect Transistors.
Creator: Pradhan, Nihar R., Garcia, Carlos, Isenberg, Bridget, Rhodes, Daniel, Feng, Simin, Memaran, Shahriar, Xin, Yan, McCreary, Amber, Walker, Angela R. Hight, Raeliarijaona, Aldo,...
Show morePradhan, Nihar R., Garcia, Carlos, Isenberg, Bridget, Rhodes, Daniel, Feng, Simin, Memaran, Shahriar, Xin, Yan, McCreary, Amber, Walker, Angela R. Hight, Raeliarijaona, Aldo, Terrones, Humberto, Terrones, Mauricio, McGill, Stephen, Balicas, Luis
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Abstract/Description: We fabricated ambipolar field-effect transistors (FETs) from multi-layered triclinic ReSe2, mechanically exfoliated onto a SiO2 layer grown on p-doped Si. In contrast to previous reports on thin layers (similar to 2 to 3 layers), we extract field-effect carrier mobilities in excess of 10(2) cm(2)/Vs at room temperature in crystals with nearly similar to 10 atomic layers. These thicker FETs also show nearly zero threshold gate voltage for conduction and high ON to OFF current ratios when...
Show moreWe fabricated ambipolar field-effect transistors (FETs) from multi-layered triclinic ReSe2, mechanically exfoliated onto a SiO2 layer grown on p-doped Si. In contrast to previous reports on thin layers (similar to 2 to 3 layers), we extract field-effect carrier mobilities in excess of 10(2) cm(2)/Vs at room temperature in crystals with nearly similar to 10 atomic layers. These thicker FETs also show nearly zero threshold gate voltage for conduction and high ON to OFF current ratios when compared to the FETs built from thinner layers. We also demonstrate that it is possible to utilize this ambipolarity to fabricate logical elements or digital synthesizers. For instance, we demonstrate that one can produce simple, gate-voltage tunable phase modulators with the ability to shift the phase of the input signal by either 90 degrees or nearly 180 degrees. Given that it is possible to engineer these same elements with improved architectures, for example on h-BN in order to decrease the threshold gate voltage and increase the carrier mobilities, it is possible to improve their characteristics in order to engineer ultra-thin layered logic elements based on ReSe2.
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Date Issued: 2018-08-24
Identifier: FSU_libsubv1_wos_000442606500032, 10.1038/s41598-018-30969-7
Format: Citation

Title: Phase Modulators Based on High Mobility Ambipolar ReSe Field-Effect Transistors.
Creator: Pradhan, Nihar R, Garcia, Carlos, Isenberg, Bridget, Rhodes, Daniel, Feng, Simin, Memaran, Shahriar, Xin, Yan, McCreary, Amber, Walker, Angela R Hight, Raeliarijaona, Aldo,...
Show morePradhan, Nihar R, Garcia, Carlos, Isenberg, Bridget, Rhodes, Daniel, Feng, Simin, Memaran, Shahriar, Xin, Yan, McCreary, Amber, Walker, Angela R Hight, Raeliarijaona, Aldo, Terrones, Humberto, Terrones, Mauricio, McGill, Stephen, Balicas, Luis
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Abstract/Description: We fabricated ambipolar field-effect transistors (FETs) from multi-layered triclinic ReSe, mechanically exfoliated onto a SiO layer grown on p-doped Si. In contrast to previous reports on thin layers (~2 to 3 layers), we extract field-effect carrier mobilities in excess of 10 cm/Vs at room temperature in crystals with nearly ~10 atomic layers. These thicker FETs also show nearly zero threshold gate voltage for conduction and high ON to OFF current ratios when compared to the FETs built from...
Show moreWe fabricated ambipolar field-effect transistors (FETs) from multi-layered triclinic ReSe, mechanically exfoliated onto a SiO layer grown on p-doped Si. In contrast to previous reports on thin layers (~2 to 3 layers), we extract field-effect carrier mobilities in excess of 10 cm/Vs at room temperature in crystals with nearly ~10 atomic layers. These thicker FETs also show nearly zero threshold gate voltage for conduction and high ON to OFF current ratios when compared to the FETs built from thinner layers. We also demonstrate that it is possible to utilize this ambipolarity to fabricate logical elements or digital synthesizers. For instance, we demonstrate that one can produce simple, gate-voltage tunable phase modulators with the ability to shift the phase of the input signal by either 90° or nearly 180°. Given that it is possible to engineer these same elements with improved architectures, for example on h-BN in order to decrease the threshold gate voltage and increase the carrier mobilities, it is possible to improve their characteristics in order to engineer ultra-thin layered logic elements based on ReSe.
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Date Issued: 2018-08-24
Identifier: FSU_pmch_30143693, 10.1038/s41598-018-30969-7, PMC6109127, 30143693, 30143693, 10.1038/s41598-018-30969-7
Format: Citation

Title: Observation Of A Pressure-induced Transition From Interlayer Ferromagnetism To Intralayer Antiferromagnetism In Sr4ru3o10.
Creator: Zheng, H., Song, W. H., Terzic, J., Zhao, H. D., Zhang, Y., Ni, Y. F., DeLong, L. E., Schlottmann, P., Cao, G.
Abstract/Description: Sr4Ru3O10 is a Ruddlesden-Popper compound with triple Ru-O perovskite layers separated by Sr-O rock-salt layers. This compound presents a rare coexistence of interlayer (c-axis) ferromagnetism and intralayer (basal-plane) metamagnetism at ambient pressure. Here we report the observation of pressure-induced, intralayer itinerant antiferromagnetism arising from the interlayer ferromagnetism. The application of modest hydrostatic pressure generates an anisotropy that may cause a flattening and a...
Show moreSr4Ru3O10 is a Ruddlesden-Popper compound with triple Ru-O perovskite layers separated by Sr-O rock-salt layers. This compound presents a rare coexistence of interlayer (c-axis) ferromagnetism and intralayer (basal-plane) metamagnetism at ambient pressure. Here we report the observation of pressure-induced, intralayer itinerant antiferromagnetism arising from the interlayer ferromagnetism. The application of modest hydrostatic pressure generates an anisotropy that may cause a flattening and a tilting of RuO6 octahedra. All magnetic and transport results from this study indicate these lattice distortions diminish the c-axis ferromagnetism and basal-plane metamagnetism, and induce a basal-plane antiferromagnetic state. The unusually large magnetoelastic coupling and pressure tunability of Sr4Ru3O10 makes it a model system for studies of itinerant magnetism.
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Date Issued: 2018-08-21
Identifier: FSU_libsubv1_wos_000442341200003, 10.1103/PhysRevB.98.064418
Format: Citation

Title: Time-reversal Symmetry-breaking Nematic Superconductivity In Fese.
Creator: Kang, Jian, Chubukov, Andrey, Fernandes, Rafael M.
Abstract/Description: FeSe is a unique member of the family of iron-based superconductors, not only because of the high values of T-c in FeSe monolayer, but also because in bulk FeSe superconductivity emerges inside a nematic phase without competing with long-range magnetic order. Near T-c, superconducting order necessarily has s + d symmetry, because nematic order couples linearly the s-wave and d-wave harmonics of the superconducting order parameter. Here we argue that the near-degeneracy between s-wave and d...
Show moreFeSe is a unique member of the family of iron-based superconductors, not only because of the high values of T-c in FeSe monolayer, but also because in bulk FeSe superconductivity emerges inside a nematic phase without competing with long-range magnetic order. Near T-c, superconducting order necessarily has s + d symmetry, because nematic order couples linearly the s-wave and d-wave harmonics of the superconducting order parameter. Here we argue that the near-degeneracy between s-wave and d-wave pairing instabilities in FeSe, combined with the sign-change of the nematic order parameter between hole and electron pockets, allows the superconducting order to break time-reversal symmetry at a temperature T* < T(c. )The transition from an s + d state to an s + e(i alpha)d state should give rise to a peak in the specific heat and to the emergence of a soft collective mode that can be potentially detected by Raman spectroscopy.
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Date Issued: 2018-08-20
Identifier: FSU_libsubv1_wos_000442194600005, 10.1103/PhysRevB.98.064508
Format: Citation

Title: Coupling integrin dynamics to cellular adhesion behaviors.
Creator: Galbraith, Catherine G, Davidson, Michael W, Galbraith, James A
Abstract/Description: Visualizing fluorescent proteins is essential for understanding cellular function. While advances in microscopy can now resolve individual molecules, determining whether the labeled molecules report native behaviors and how the measured behaviors can be coupled to cellular outputs remains challenging. Here, we used integrin alpha-beta heterodimers - which connect extracellular matrix (ECM) and the cytoskeleton - to quantify the mobility and conformation of labeled integrins. We found that...
Show moreVisualizing fluorescent proteins is essential for understanding cellular function. While advances in microscopy can now resolve individual molecules, determining whether the labeled molecules report native behaviors and how the measured behaviors can be coupled to cellular outputs remains challenging. Here, we used integrin alpha-beta heterodimers - which connect extracellular matrix (ECM) and the cytoskeleton - to quantify the mobility and conformation of labeled integrins. We found that while unlabeled and labeled integrins all localized to adhesions and support anchorage-dependent cell function, integrin mobility decreased when the beta rather than the alpha subunit was labeled. In contrast to unlabeled and alpha labeled subunits, beta labeled subunits changed cellular behavior; decreasing protrusive activity and increasing adhesion size and the extent of cell spreading. Labeling the beta subunit changed the integrin conformation, extending the molecule and exposing an epitope that is revealed by activation with Mn treatment. Our findings indicate labeling induced changes in dynamic integrin behavior alter molecular conformation as well as cellular adhesion-dependent function to demonstrate a coupling between molecular inputs and distinct cellular outputs.This article has an associated First Person interview with the first author of the paper.
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Date Issued: 2018-08-15
Identifier: FSU_pmch_30111545, 10.1242/bio.036806, PMC6124568, 30111545, 30111545, 7/8/bio036806
Format: Citation

Title: Fermi Surface Reconstruction And Dimensional Topology Change In Nd-doped Cecoin5.
Creator: Klotz, J., Goetze, K., Sheikin, I., Foerster, T., Graf, D., Park, J.-H., Choi, E. S., Hu, R., Petrovic, C., Wosnitza, J., Green, E. L.
Abstract/Description: We performed low-temperature de Haas-van Alphen effect measurements on a Ce1-xNdxCoIn5 series, for x = 0.02, 0.05, 0.1, and 1, down to T = 40 mK using torque magnetometry in magnetic fields up to 35 T. Our results indicate that a Fermi surface (FS) reconstruction occurs from a quasi-two-dimensional topology for Nd-2% to a rather three-dimensional one for Nd-5%, thus reducing the possibility of perfect FS nesting. The FS evolves further with increasing Nd content with no observed divergence of...
Show moreWe performed low-temperature de Haas-van Alphen effect measurements on a Ce1-xNdxCoIn5 series, for x = 0.02, 0.05, 0.1, and 1, down to T = 40 mK using torque magnetometry in magnetic fields up to 35 T. Our results indicate that a Fermi surface (FS) reconstruction occurs from a quasi-two-dimensional topology for Nd-2% to a rather three-dimensional one for Nd-5%, thus reducing the possibility of perfect FS nesting. The FS evolves further with increasing Nd content with no observed divergence of the effective mass between Nd-2% and 10%, consistent with the crossing of a spin density wave type of quantum critical point. Our results elucidate the origin of the Q phase observed at the 5% Nd-doping level [Raymond et al., T. Phys. Soc. Jpn. 83, 013707 (2014)].
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Date Issued: 2018-08-09
Identifier: FSU_libsubv1_wos_000441234900001, 10.1103/PhysRevB.98.081105
Format: Citation

Title: High-field Magnetoresistance Of Organic Semiconductors.
Creator: Joshi, G., Teferi, M. Y., Miller, R., Jamali, S., Groesbeck, M., van Tol, J., McLaughlin, R., Vardeny, Z. V., Lupton, J. M., Malissa, H., Boehme, C.
Abstract/Description: The magnetoelectronic field effects in organic semiconductors at high magnetic fields are described by field-dependent mixing between singlet and triplet states of weakly bound charge-carrier pairs due to small differences in their Lande g factors that arise from the weak spin-orbit coupling in the material. In this work, we corroborate theoretical models for the high-field magnetoresistance of organic semiconductors, in particular of diodes made of the conducting polymer poly(3,4...
Show moreThe magnetoelectronic field effects in organic semiconductors at high magnetic fields are described by field-dependent mixing between singlet and triplet states of weakly bound charge-carrier pairs due to small differences in their Lande g factors that arise from the weak spin-orbit coupling in the material. In this work, we corroborate theoretical models for the high-field magnetoresistance of organic semiconductors, in particular of diodes made of the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) at low temperatures, by conducting magnetoresistance measurements along with multifrequency continuous-wave electrically detected magnetic-resonance experiments. The measurements are performed on identical devices under similar conditions in order to independently assess the magnetic-field-dependent spin-mixing mechanism, the so-called Delta g mechanism. An understanding of the microscopic origin of magnetoresistance in organic semiconductors is crucial for developing reliable magnetometer devices capable of operating over a broad range of magnetic fields of order 10(-7)-10 T.
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Date Issued: 2018-08-09
Identifier: FSU_libsubv1_wos_000441238900001, 10.1103/PhysRevApplied.10.024008
Format: Citation

Title: Observation Of Two Critical Points Linked To The High-field Phase B In Cecu2si2.
Creator: Weickert, Franziska, Gegenwart, Philipp, Geibel, Christoph, Assmus, Wolf, Steglich, Frank
Abstract/Description: We present thermal expansion and magnetostriction measurements on a CeCu2Si2 single crystal of A/S type up to 17.9 T magnetic field applied along the crystallographic a direction (Delta L parallel to a parallel to H) and down to 0.015 K temperature. We identify clear thermodynamic anomalies at the superconducting transition T-c and at two second-order transitions T-A,T-B into ordered phases A and B. Our measurements establish the boundary of phase B at high field and low temperature. No...
Show moreWe present thermal expansion and magnetostriction measurements on a CeCu2Si2 single crystal of A/S type up to 17.9 T magnetic field applied along the crystallographic a direction (Delta L parallel to a parallel to H) and down to 0.015 K temperature. We identify clear thermodynamic anomalies at the superconducting transition T-c and at two second-order transitions T-A,T-B into ordered phases A and B. Our measurements establish the boundary of phase B at high field and low temperature. No evidence for additional high-field phases above B is found up to the maximum field. We speculate based on our experimental results that (i) phase B is similar to phase A of spin-density wave type and (ii) the first-order phase transition between A and B is caused by Fermi-surface reconstruction. We furthermore identify a quantum critical point at H-c similar or equal to 17 T, where T-B is suppresssed to zero, and a bicritical point at (0.35 K, 7.0 T), where phase lines T-A(H) and T-B(H) meet.
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Date Issued: 2018-08-08
Identifier: FSU_libsubv1_wos_000441108600002, 10.1103/PhysRevB.98.085115
Format: Citation

Title: Relative Contributions of and Bacteriophage to Bacterial Cell Death under Various Environmental Conditions.
Creator: Chen, Huan, Laws, Edward A, Martin, Julio L, Berhane, Timkhite-Kulu, Gulig, Paul A, Williams, Henry N
Abstract/Description: The role of protists and bacteriophages in bacterial predation in the microbial food web has been well studied. There is mounting evidence that and like organisms (BALOs) also contribute to bacterial mortality and, in some cases, more so than bacteriophages. A full understanding of the ecologic function of the microbial food web requires recognition of all major predators and the magnitude of each predator's contribution. Here we investigated the contribution of , one of the BALOs, and...
Show moreThe role of protists and bacteriophages in bacterial predation in the microbial food web has been well studied. There is mounting evidence that and like organisms (BALOs) also contribute to bacterial mortality and, in some cases, more so than bacteriophages. A full understanding of the ecologic function of the microbial food web requires recognition of all major predators and the magnitude of each predator's contribution. Here we investigated the contribution of , one of the BALOs, and bacteriophages when incubated with their common prey, , in a seawater microcosm. We observed that was the greatest responder to the prey, increasing 18-fold with a simultaneous 4.4-log-unit reduction of at 40 h, whereas the bacteriophage population showed no significant increase. In subsequent experiments to formulate a medium that would support the predatory activities and replication of both predators, low-nutrient media favored the predation and replication of the , whereas higher-nutrient media enhanced phage growth. The greatest prey reduction and replication of both and phage were observed in media with moderate nutrient levels. Additional experiments show that the predatory activities of both predators were influenced by environmental conditions, specifically, temperature and salinity. The two predators combined exerted greater control on , a synergism that may be exploited for practical applications to reduce bacterial populations. These findings suggest that along with bacteriophage and protists, has the potential to have a prominent role in bacterial mortality and cycling of nutrients, two vital ecologic functions. Although much has been reported about the marine microbial food web and the role of micropredators, specifically viruses and protists, the contribution of -like predators has largely been ignored, posing a major gap in understanding food web processes. A complete scenario of the microbial food web cannot be developed until the roles of all major micropredators and the magnitude of their contributions to bacterial mortality, structuring of microbial communities, and cycling of nutrients are assessed. Here we show compelling evidence that , a predatory bacterium, is a significant contributor to bacterial death and, in some cases, may rival viruses as agents of bacterial mortality. These results advance current understanding of the microbial loop and top-down control on the bacterial community.
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Date Issued: 2018-08-07
Identifier: FSU_pmch_30087166, 10.1128/mBio.01202-18, PMC6083911, 30087166, 30087166, mBio.01202-18
Format: Citation

Title: Low-energy Excitations In Quantum Spin Liquids Identified By Optical Spectroscopy.
Creator: Pustogow, A., Saito, Y., Zhukova, E., Gorshunov, B., Kato, R., Lee, T.-H., Fratini, S., Dobrosavljevic, V., Dressel, M.
Abstract/Description: The electrodynamic response of organic spin liquids with highly frustrated triangular lattices has been measured in a wide energy range. While the overall optical spectra of these Mott insulators are governed by transitions between the Hubbard bands, distinct in-gap excitations can be identified at low temperatures and frequencies, which we attribute to the quantum-spin-liquid state. For the strongly correlated ss'-EtMe3Sb[Pd(dmit)(2)](2), we discover enhanced conductivity below 175 cm(-1),...
Show moreThe electrodynamic response of organic spin liquids with highly frustrated triangular lattices has been measured in a wide energy range. While the overall optical spectra of these Mott insulators are governed by transitions between the Hubbard bands, distinct in-gap excitations can be identified at low temperatures and frequencies, which we attribute to the quantum-spin-liquid state. For the strongly correlated ss'-EtMe3Sb[Pd(dmit)(2)](2), we discover enhanced conductivity below 175 cm(-1), comparable to the energy of the magnetic coupling J approximate to 250 K. For omega -> 0, these low-frequency excitations vanish faster than the charge-carrier response subject to Mott-Hubbard correlations, resulting in a dome-shaped band peaked at 100 cm(-1). Possible relations to spinons, magnons, and disorder are discussed.
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Date Issued: 2018-08-03
Identifier: FSU_libsubv1_wos_000440724200014, 10.1103/PhysRevLett.121.056402
Format: Citation

Title: Lipid Extraction By Alpha-synuclein Generates Semi-transmembrane Defects And Lipoprotein Nanoparticles.
Creator: Pan, Jianjun, Dalzini, Annalisa, Khadka, Nawal K., Aryal, Chinta M., Song, Likai
Abstract/Description: Modulations of synaptic membranes play an essential role in the physiological and pathological functions of the presynaptic protein alpha-synuclein (alpha Syn). Here we used solution atomic force microscopy (AFM) and electron paramagnetic resonance (EPR) spectroscopy to investigate membrane modulations caused by alpha Syn. We used several lipid bilayers to explore how different lipid species may regulate alpha Syn-membrane interactions. We found that at a protein-to-lipid ratio of similar to...
Show moreModulations of synaptic membranes play an essential role in the physiological and pathological functions of the presynaptic protein alpha-synuclein (alpha Syn). Here we used solution atomic force microscopy (AFM) and electron paramagnetic resonance (EPR) spectroscopy to investigate membrane modulations caused by alpha Syn. We used several lipid bilayers to explore how different lipid species may regulate alpha Syn-membrane interactions. We found that at a protein-to-lipid ratio of similar to 1/9, alpha Syn perturbed lipid bilayers by generating semi-transmembrane defects that only span one leaflet. In addition, alpha Syn coaggregates with lipid molecules to produce similar to 10 nm-sized lipoprotein nanoparticles. The obtained AFM data are consistent with the apolipoprotein characteristic of alpha Syn. The role of anionic lipids was elucidated by comparing results from zwitterionic and anionic lipid bilayers. Specifically, our AFM measurements showed that anionic bilayers had a larger tendency of forming bilayer defects; similarly, our EPR measurements revealed that anionic bilayers exhibited more substantial changes in lipid chain mobility and bilayer polarity. We also studied the effect of cholesterol. We found that cholesterol increased the capability of alpha Syn in inducing bilayer defects and altering lipid chain mobility and bilayer polarity. These data can be explained by an increase in the lipid headgroup-headgroup spacing and/or specific cholesterol-alpha Syn interactions. Interestingly, we found an inhibitory effect of the cone-shaped phosphatidylethanolamine lipids on alpha Syn-induced bilayer remodeling. We explained our data by considering interlipid hydrogen-bonding that can stabilize bilayer organization and suppress lipid extraction. Our results of lipid-dependent membrane modulations are likely relevant to alpha Syn functioning.
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Date Issued: 2018-08-01
Identifier: FSU_libsubv1_wos_000444182900101, 10.1021/acsomega.8b01462
Format: Citation

Title: Coupling Integrin Dynamics To Cellular Adhesion Behaviors.
Creator: Galbraith, Catherine G., Davidson, Michael W., Galbraith, James A.
Abstract/Description: Visualizing fluorescent proteins is essential for understanding cellular function. While advances in microscopy can now resolve individual molecules, determining whether the labeled molecules report native behaviors and how the measured behaviors can be coupled to cellular outputs remains challenging. Here, we used integrin alphabeta heterodimers - which connect extracellular matrix (ECM) and the cytoskeleton - to quantify the mobility and conformation of labeled integrins. We found that...
Show moreVisualizing fluorescent proteins is essential for understanding cellular function. While advances in microscopy can now resolve individual molecules, determining whether the labeled molecules report native behaviors and how the measured behaviors can be coupled to cellular outputs remains challenging. Here, we used integrin alphabeta heterodimers - which connect extracellular matrix (ECM) and the cytoskeleton - to quantify the mobility and conformation of labeled integrins. We found that while unlabeled and labeled integrins all localized to adhesions and support anchorage-dependent cell function, integrin mobility decreased when the beta rather than the alpha subunit was labeled. In contrast to unlabeled and alpha labeled subunits, beta labeled subunits changed cellular behavior, decreasing protrusive activity and increasing adhesion size and the extent of cell spreading. Labeling the beta subunit changed the integrin conformation, extending the molecule and exposing an epitope that is revealed by activation with Mn2+ treatment. Our findings indicate labeling induced changes in dynamic integrin behavior alter molecular conformation as well as cellular adhesion-dependent function to demonstrate a coupling between molecular inputs and distinct cellular outputs. This article has an associated First Person interview with the first author of the paper.
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Date Issued: 2018-08-01
Identifier: FSU_libsubv1_wos_000443455200017, 10.1242/bio.036806
Format: Citation

Title: The Nature Of Spin Excitations In The One-third Magnetization Plateau Phase Of Ba3cosb2o9 (vol 9, 2666, 2018).
Creator: Kamiya, Y., Ge, L., Hong, Tao, Qiu, Y., Quintero-Castro, D. L., Lu, Z., Cao, H. B., Matsuda, M., Choi, E. S., Batista, C. D., Mourigal, M., Zhou, H. D., Ma, J.
Date Issued: 2018-08-01
Identifier: FSU_libsubv1_wos_000440414100002, 10.1038/s41467-018-05679-3
Format: Citation

Title: Relative Contributions Of Halobacteriovorax And Bacteriophage To Bacterial Cell Death Under Various Environmental Conditions.
Creator: Chen, Huan, Laws, Edward A., Martin, Julio L., Berhane, Timkhite-Kulu, Gulig, Paul A., Williams, Henry N.
Abstract/Description: The role of protists and bacteriophages in bacterial predation in the microbial food web has been well studied. There is mounting evidence that Bdellovibrio and like organisms (BALOs) also contribute to bacterial mortality and, in some cases, more so than bacteriophages. A full understanding of the ecologic function of the microbial food web requires recognition of all major predators and the magnitude of each predator's contribution. Here we investigated the contribution of Halobacteriovorax...
Show moreThe role of protists and bacteriophages in bacterial predation in the microbial food web has been well studied. There is mounting evidence that Bdellovibrio and like organisms (BALOs) also contribute to bacterial mortality and, in some cases, more so than bacteriophages. A full understanding of the ecologic function of the microbial food web requires recognition of all major predators and the magnitude of each predator's contribution. Here we investigated the contribution of Halobacteriovorax, one of the BALOs, and bacteriophages when incubated with their common prey, Vibrio vulnificus, in a seawater microcosm. We observed that Halobacteriovorax was the greatest responder to the prey, increasing 18-fold with a simultaneous 4.4-log-unit reduction of V. vulnificus at 40 h, whereas the bacteriophage population showed no significant increase. In subsequent experiments to formulate a medium that would support the predatory activities and replication of both predators, low-nutrient media favored the predation and replication of the Halobacteriovorax, whereas higher-nutrient media enhanced phage growth. The greatest prey reduction and replication of both Halobacteriovorax and phage were observed in media with moderate nutrient levels. Additional experiments show that the predatory activities of both predators were influenced by environmental conditions, specifically, temperature and salinity. The two predators combined exerted greater control on V. vulnificus, a synergism that may be exploited for practical applications to reduce bacterial populations. These findings suggest that along with bacteriophage and protists, Halobacteriovorax has the potential to have a prominent role in bacterial mortality and cycling of nutrients, two vital ecologic functions. IMPORTANCE Although much has been reported about the marine microbial food web and the role of micropredators, specifically viruses and protists, the contribution of Bdellovibrio-like predators has largely been ignored, posing a major gap in understanding food web processes. A complete scenario of the microbial food web cannot be developed until the roles of all major micropredators and the magnitude of their contributions to bacterial mortality, structuring of microbial communities, and cycling of nutrients are assessed. Here we show compelling evidence that Halobacteriovorax, a predatory bacterium, is a significant contributor to bacterial death and, in some cases, may rival viruses as agents of bacterial mortality. These results advance current understanding of the microbial loop and top-down control on the bacterial community.
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Date Issued: 2018-08-01
Identifier: FSU_libsubv1_wos_000443884300043, 10.1128/mBio.01202-18
Format: Citation

Title: Author Correction: The nature of spin excitations in the one-third magnetization plateau phase of BaCoSbO..
Creator: Kamiya, Y, Ge, L, Hong, Tao, Qiu, Y, Quintero-Castro, D L, Lu, Z, Cao, H B, Matsuda, M, Choi, E S, Batista, C D, Mourigal, M, Zhou, H D, Ma, J
Abstract/Description: The original version of this Article omitted the following from the Acknowledgements: 'J. Ma's primary affiliation is Shanghai Jiao Tong University.' This has been corrected in both the PDF and HTML versions of the Article.
Date Issued: 2018-08-01
Identifier: FSU_pmch_30068947, 10.1038/s41467-018-05679-3, PMC6070534, 30068947, 30068947, 10.1038/s41467-018-05679-3
Format: Citation

Title: Interplay Of Magnetism And Transport In Hobi.
Creator: Yang, H.-Y., Gaudet, J., Aczel, A. A., Graf, D. E., Blaha, P., Gaulin, B. D., Tafti, Fazel
Abstract/Description: We report the observation of an extreme magnetoresistance (XMR) in HoBi with a large magnetic moment from Ho f electrons. Neutron scattering is used to determine the magnetic wave vectors across several metamagnetic transitions on the phase diagram of HoBi. Unlike other magnetic rare-earth monopnictides, the field dependence of resistivity in HoBi is nonmonotonic and reveals clear signatures of every metamagnetic transition in the low-temperature and low-field regime, at T 2.3 T after all...
Show moreWe report the observation of an extreme magnetoresistance (XMR) in HoBi with a large magnetic moment from Ho f electrons. Neutron scattering is used to determine the magnetic wave vectors across several metamagnetic transitions on the phase diagram of HoBi. Unlike other magnetic rare-earth monopnictides, the field dependence of resistivity in HoBi is nonmonotonic and reveals clear signatures of every metamagnetic transition in the low-temperature and low-field regime, at T < 2 K and H < 2.3 T. The XMR appears at H > 2.3 T after all the metamagnetic transitions are complete and the system is spin polarized by the external magnetic field. The existence of an onset field for XMR and the intimate connection between magnetism and transport in HoBi are unprecedented among the magnetic rare-earth monopnictides. Therefore, HoBi provides a unique opportunity to understand the electrical transport in magnetic XMR semimetals.
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Date Issued: 2018-07-27
Identifier: FSU_libsubv1_wos_000439974200002, 10.1103/PhysRevB.98.045136
Format: Citation

Title: 1.1-billion-year-old Porphyrins Establish A Marine Ecosystem Dominated By Bacterial Primary Producers.
Creator: Gueneli, N., McKenna, A. M., Ohkouchi, N., Boreham, C. J., Beghin, J., Javaux, E. J., Brocks, J. J.
Abstract/Description: The average cell size of marine phytoplankton is critical for the flow of energy and nutrients from the base of the food web to higher trophic levels. Thus, the evolutionary succession of primary producers through Earth's history is important for our understanding of the radiation of modern protists similar to 800 million years ago and the emergence of eumetazoan animals similar to 200 million years later. Currently, it is difficult to establish connections between primary production and the...
Show moreThe average cell size of marine phytoplankton is critical for the flow of energy and nutrients from the base of the food web to higher trophic levels. Thus, the evolutionary succession of primary producers through Earth's history is important for our understanding of the radiation of modern protists similar to 800 million years ago and the emergence of eumetazoan animals similar to 200 million years later. Currently, it is difficult to establish connections between primary production and the proliferation of large and complex organisms because the mid-Proterozoic (similar to 1,800-800 million years ago) rock record is nearly devoid of recognizable phytoplankton fossils. We report the discovery of intact porphyrins, the molecular fossils of chlorophylls, from 1,100-million-year-old marine black shales of the Taoudeni Basin (Mauritania), 600 million years older than previous findings. The porphyrin nitrogen isotopes (delta N-15(por) = 5.6-10.2 parts per thousand) are heavier than in younger sedimentary sequences, and the isotopic offset between sedimentary bulk nitrogen and porphyrins (epsilon(por) = -5.1 to -0.5 parts per thousand) points to cyanobacteria as dominant primary producers. Based on fossil carotenoids, anoxygenic green (Chlorobiacea) and purple sulfur bacteria (Chromatiaceae) also contributed to photosynthate. The low epsilon(por) values, in combination with a lack of diagnostic eukaryotic steranes in the time interval of 1,600-1,000 million years ago, demonstrate that algae played an insignificant role in mid-Proterozoic oceans. The paucity of algae and the small cell size of bacterial phytoplankton may have curtailed the flow of energy to higher trophic levels, potentially contributing to a diminished evolutionary pace toward complex eukaryotic ecosystems and large and active organisms.
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Date Issued: 2018-07-24
Identifier: FSU_libsubv1_wos_000439574700004, 10.1073/pnas.1803866115
Format: Citation

Title: Cellular and molecular responses to acute cocaine treatment in neuronal-like N2a cells: potential mechanism for its resistance in cell death..
Creator: Badisa, Ramesh B, Wi, Sungsool, Jones, Zachary, Mazzio, Elizabeth, Zhou, Yi, Rosenberg, Jens T, Latinwo, Lekan M, Grant, Samuel C, Goodman, Carl B
Abstract/Description: Cocaine is a highly abused drug that causes psychiatric and neurological problems. Its entry into neurons could alter cell-biochemistry and contribute in the manifestation of early pathological symptoms. We have previously shown the acute cocaine effects in rat C6 astroglia-like cells and found that these cells were highly sensitive to cocaine in terms of manifesting certain pathologies known to underlie psychological disorders. The present study was aimed to discern acute cocaine effects on...
Show moreCocaine is a highly abused drug that causes psychiatric and neurological problems. Its entry into neurons could alter cell-biochemistry and contribute in the manifestation of early pathological symptoms. We have previously shown the acute cocaine effects in rat C6 astroglia-like cells and found that these cells were highly sensitive to cocaine in terms of manifesting certain pathologies known to underlie psychological disorders. The present study was aimed to discern acute cocaine effects on the early onset of various changes in Neuro-2a (N2a) cells. Whole-cell patch-clamp recording of differentiated cells displayed the functional voltage-gated Na and K channels, which demonstrated the neuronal characteristics of the cells. Treatment of these cells with acute cocaine (1 h) at in vivo (nM to μM) and in vitro (mM) concentrations revealed that the cells remained almost 100% viable. Cocaine administration at 6.25 μM or 4 mM doses significantly reduced the inward currents but had no significant effect on outward currents, indicating the Na channel-blocking activity of cocaine. While no morphological change was observed at in vivo doses, treatment at in vitro doses altered the morphology, damaged the neurites, and induced cytoplasmic vacuoles; furthermore, general mitochondrial activity and membrane potential were significantly decreased. Mitochondrial dysfunction enabled the cells switch to anaerobic glycolysis, evidenced by dose-dependent increases in lactate and HS, resulting unaltered ATP level in the cells. Further investigation on the mechanism of action unfolded that the cell's resistance to cocaine was through the activation of nuclear factor E2-related factor-2 () gene and subsequent increase of antioxidants (glutathione [GSH], catalase and GSH peroxidase [GPx]). The data clearly indicate that the cells employed a detoxifying strategy against cocaine. On a broader perspective, we envision that extrapolating the knowledge of neuronal resistance to central nervous system (CNS) diseases could delay their onset or progression.
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Date Issued: 2018-07-17
Identifier: FSU_pmch_30210816, 10.1038/s41420-018-0078-x, PMC6133924, 30210816, 30210816, 78
Format: Citation

Title: Multiple Topologically Nontrivial Bands In Noncentrosymmetric Ysn2.
Creator: Zhu, Yanglin, Zhang, Tiantian, Hu, Jin, Kidd, Jamin, Graf, David, Gui, Xin, Xie, Weiwei, Zhu, Mengze, Ke, Xianglin, Cao, Huibo, Fang, Zhong, Weng, Hongming, Mao, Zhiqiang
Abstract/Description: The square lattices formed by main-group elements such as Bi, Sb, Sn, and Si in layered materials have attracted a lot of interest, since they can create rich topological phases. In this paper, we report the slightly distorted square lattice of Sn in a noncentrosymmetric compound YSn2 generates multiple topologically nontrivial bands, one of which likely hosts a nodal line and tunable Weyl semimetal state induced by the Rashba spin-orbit coupling and proper external magnetic field. The...
Show moreThe square lattices formed by main-group elements such as Bi, Sb, Sn, and Si in layered materials have attracted a lot of interest, since they can create rich topological phases. In this paper, we report the slightly distorted square lattice of Sn in a noncentrosymmetric compound YSn2 generates multiple topologically nontrivial bands, one of which likely hosts a nodal line and tunable Weyl semimetal state induced by the Rashba spin-orbit coupling and proper external magnetic field. The quasiparticles described as relativistic fermions from these bands are manifested by nearly zero mass and nontrivial Berry phases probed in de Haas-van Alphen (dHvA) oscillations. The dHvA study also reveals YSn2 has a complicated Fermi surface, consisting of several three-dimensional (3D) and one 2D pocket. Our first-principles calculations show the pointlike 3D pocket at Y point on the Brillouin zone boundary hosts the possible Weyl state. Our findings establish YSn2 as a new interesting platform for observing novel topological phases and studying their underlying physics.
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Date Issued: 2018-07-16
Identifier: FSU_libsubv1_wos_000438674700001, 10.1103/PhysRevB.98.035117
Format: Citation

Title: Energy-level Statistics In Strongly Disordered Systems With Power-law Hopping.
Creator: Titum, Paraj, Quito, Victor L., Syzranov, Sergey
Abstract/Description: Motivated by neutral excitations in disordered electronic materials and systems of trapped ultracold particles with long-range interactions, we study energy-level statistics of quasiparticles with the power-law hopping Hamiltonian proportional to 1/r(alpha) in a strong random potential. In solid-state systems such quasiparticles, which are exemplified by neutral dipolar excitations, lead to long-range correlations of local observables and may dominate energy transport. Focusing on the...
Show moreMotivated by neutral excitations in disordered electronic materials and systems of trapped ultracold particles with long-range interactions, we study energy-level statistics of quasiparticles with the power-law hopping Hamiltonian proportional to 1/r(alpha) in a strong random potential. In solid-state systems such quasiparticles, which are exemplified by neutral dipolar excitations, lead to long-range correlations of local observables and may dominate energy transport. Focusing on the excitations in disordered electronic systems, we compute the energy-level correlation function R-2(omega) in a finite system in the limit of sufficiently strong disorder. At small energy differences, the correlations exhibit Wigner-Dyson statistics. In particular, in the limit of very strong disorder the energy-level correlation function is given by R-2(omega, V) = A(3) omega/omega(V) for small frequencies omega << omega(V) and R-2(omega, V) = 1 - (alpha - d)A(1) (omega(V)/omega)(d/alpha) - A(2) (omega(V)/omega)(2) for large frequencies omega << omega(V), where omega(V) proportional to V-alpha/d is the characteristic matrix element of excitation hopping in a system of volume V, and A(1), A(2), and A(3) are coefficients of order unity which depend on the shape of the system. The energy-level correlation function, which we study, allows for a direct experimental observation, for example, by measuring the correlations of the ac conductance of the system at different frequencies.
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Date Issued: 2018-07-16
Identifier: FSU_libsubv1_wos_000438672400001, 10.1103/PhysRevB.98.014201
Format: Citation

Title: Molecular Architecture Of Fungal Cell Walls Revealed By Solid-state Nmr.
Creator: Kang, Xue, Kirui, Alex, Muszynski, Artur, Widanage, Malitha C. Dickwella, Chen, Adrian, Azadi, Parastoo, Wang, Ping, Mentink-Vigier, Frederic, Wang, Tuo
Abstract/Description: The high mortality of invasive fungal infections, and the limited number and inefficacy of antifungals necessitate the development of new agents with novel mechanisms and targets. The fungal cell wall is a promising target as it contains polysaccharides absent in humans, however, its molecular structure remains elusive. Here we report the architecture of the cell walls in the pathogenic fungus Aspergillus fumigatus. Solid-state NMR spectroscopy, assisted by dynamic nuclear polarization and...
Show moreThe high mortality of invasive fungal infections, and the limited number and inefficacy of antifungals necessitate the development of new agents with novel mechanisms and targets. The fungal cell wall is a promising target as it contains polysaccharides absent in humans, however, its molecular structure remains elusive. Here we report the architecture of the cell walls in the pathogenic fungus Aspergillus fumigatus. Solid-state NMR spectroscopy, assisted by dynamic nuclear polarization and glycosyl linkage analysis, reveals that chitin and alpha-1,3-glucan build a hydrophobic scaffold that is surrounded by a hydrated matrix of diversely linked beta-glucans and capped by a dynamic layer of glycoproteins and alpha-1,3-glucan. The two-domain distribution of alpha-1,3-glucans signifies the dual functions of this molecule: contributing to cell wall rigidity and fungal virulence. This study provides a high-resolution model of fungal cell walls and serves as the basis for assessing drug response to promote the development of wall-targeted antifungals.
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Date Issued: 2018-07-16
Identifier: FSU_libsubv1_wos_000438683800005, 10.1038/s41467-018-05199-0
Format: Citation

Title: Imaging The Magnetic States In An Actinide Ferromagnet Umn2ge2.
Creator: Tan, Xinzhou, Berg, Morgann, de Lozanne, Alex, Kim, Jeehoon, Baumbach, R. E., Bauer, E. D., Thompson, J. D., Ronning, F.
Abstract/Description: We present studies of the magnetic domain structure of UMn2Ge2 single crystals using a home-built low temperature magnetic force microscope. The material has two distinct magnetic ordering temperatures, originating from the Mn and U moments. At room temperature, where the Mn moments dominate, there are flowerlike domain patterns similar to those observed in uniaxial ferromagnets. After exposing the sample to a 1 T magnetic field near 40 K, the evolution of the magnetic domains are imaged...
Show moreWe present studies of the magnetic domain structure of UMn2Ge2 single crystals using a home-built low temperature magnetic force microscope. The material has two distinct magnetic ordering temperatures, originating from the Mn and U moments. At room temperature, where the Mn moments dominate, there are flowerlike domain patterns similar to those observed in uniaxial ferromagnets. After exposing the sample to a 1 T magnetic field near 40 K, the evolution of the magnetic domains are imaged through zero-field warming up to 210 K. Near the ordering temperature of the uranium moments a clear change in the domain wall motion is observed. The domain size analysis of the flowerlike pattern reveals that the domain structure is consistent with a model of branching domains.
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Date Issued: 2018-07-11
Identifier: FSU_libsubv1_wos_000438196300003, 10.1103/PhysRevMaterials.2.074402
Format: Citation

Title: The nature of spin excitations in the one-third magnetization plateau phase of BaCoSbO.
Creator: Kamiya, Y, Ge, L, Hong, Tao, Qiu, Y, Quintero-Castro, D L, Lu, Z, Cao, H B, Matsuda, M, Choi, E S, Batista, C D, Mourigal, M, Zhou, H D, Ma, J
Abstract/Description: Magnetization plateaus in quantum magnets-where bosonic quasiparticles crystallize into emergent spin superlattices-are spectacular yet simple examples of collective quantum phenomena escaping classical description. While magnetization plateaus have been observed in a number of spin-1/2 antiferromagnets, the description of their magnetic excitations remains an open theoretical and experimental challenge. Here, we investigate the dynamical properties of the triangular-lattice spin-1/2...
Show moreMagnetization plateaus in quantum magnets-where bosonic quasiparticles crystallize into emergent spin superlattices-are spectacular yet simple examples of collective quantum phenomena escaping classical description. While magnetization plateaus have been observed in a number of spin-1/2 antiferromagnets, the description of their magnetic excitations remains an open theoretical and experimental challenge. Here, we investigate the dynamical properties of the triangular-lattice spin-1/2 antiferromagnet BaCoSbO in its one-third magnetization plateau phase using a combination of nonlinear spin-wave theory and neutron scattering measurements. The agreement between our theoretical treatment and the experimental data demonstrates that magnons behave semiclassically in the plateau in spite of the purely quantum origin of the underlying magnetic structure. This allows for a quantitative determination of BaCoSbO exchange parameters. We discuss the implication of our results to the deviations from semiclassical behavior observed in zero-field spin dynamics of the same material and conclude they must have an intrinsic origin.
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Date Issued: 2018-07-10
Identifier: FSU_pmch_29991805, 10.1038/s41467-018-04914-1, PMC6039502, 29991805, 29991805, 10.1038/s41467-018-04914-1
Format: Citation

Title: Spin-phonon Couplings In Transition Metal Complexes With Slow Magnetic Relaxation.
Creator: Moseley, Duncan H., Stavretis, Shelby E., Thirunavukkuarasu, Komalavalli, Ozerov, Mykhaylo, Cheng, Yongqiang, Daemen, Luke L., Ludwig, Jonathan, Lu, Zhengguang, Smirnov, Dmitry,...
Show moreMoseley, Duncan H., Stavretis, Shelby E., Thirunavukkuarasu, Komalavalli, Ozerov, Mykhaylo, Cheng, Yongqiang, Daemen, Luke L., Ludwig, Jonathan, Lu, Zhengguang, Smirnov, Dmitry, Brown, Craig M., Pandey, Anup, Ramirez-Cuesta, A. J., Lamb, Adam C., Atanasov, Mihail, Bill, Eckhard, Neese, Frank, Xue, Zi-Ling
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Abstract/Description: Spin-phonon coupling plays an important role in single-molecule magnets and molecular qubits. However, there have been few detailed studies of its nature. Here, we show for the first time distinct couplings of g phonons of Co-II(acac)(2)(H2O)(2) (acac = acetylacetonate) and its deuterated analogs with zero-field-split, excited magnetic/spin levels (Kramers doublet (KD)) of the S = 3/2 electronic ground state. The couplings are observed as avoided crossings in magnetic-field-dependent Raman...
Show moreSpin-phonon coupling plays an important role in single-molecule magnets and molecular qubits. However, there have been few detailed studies of its nature. Here, we show for the first time distinct couplings of g phonons of Co-II(acac)(2)(H2O)(2) (acac = acetylacetonate) and its deuterated analogs with zero-field-split, excited magnetic/spin levels (Kramers doublet (KD)) of the S = 3/2 electronic ground state. The couplings are observed as avoided crossings in magnetic-field-dependent Raman spectra with coupling constants of 1-2 cm(-1). Far-IR spectra reveal the magnetic-dipole-allowed, inter-KD transition, shifting to higher energy with increasing field. Density functional theory calculations are used to rationalize energies and symmetries of the phonons. A vibronic coupling model, supported by electronic structure calculations, is proposed to rationalize the behavior of the coupled Raman peaks. This work spectroscopically reveals and quantitates the spin-phonon couplings in typical transition metal complexes and sheds light on the origin of the spin-phonon entanglement.
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Date Issued: 2018-07-03
Identifier: FSU_libsubv1_wos_000437101700002, 10.1038/s41467-018-04896-0
Format: Citation

Title: Broadband Ultrafast Terahertz Spectroscopy In The 25 T Split Florida-helix.
Creator: Curtis, Jeremy A., Burch, Ashlyn D., Barman, Biplob, Linn, A. Garrison, McClintock, Luke M., O'Beirne, Aidan L., Stiles, Matthew J., Reno, John L., McGill, Stephen A., Karaiskaj...
Show moreCurtis, Jeremy A., Burch, Ashlyn D., Barman, Biplob, Linn, A. Garrison, McClintock, Luke M., O'Beirne, Aidan L., Stiles, Matthew J., Reno, John L., McGill, Stephen A., Karaiskaj, Denis, Hilton, David J.
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Abstract/Description: We describe the development of a broadband (0.3-10 THz) optical pump-terahertz probe spectrometer with an unprecedented combination of temporal resolution (<= 200 fs) operating in external magnetic fields as high as 25 T using the new Split Florida-Helix magnet system. Using this new instrument, we measure the transient dynamics in a gallium arsenide four-quantum well sample after photoexcitation at 800 nm. Published by AIP Publishing.
Date Issued: 2018-07-01
Identifier: FSU_libsubv1_wos_000440590200028, 10.1063/1.5023384
Format: Citation

Title: Detailed Study Of The Fermi Surfaces Of The Type-ii Dirac Semimetallic Candidates Xte2 (x=pd,pt).
Creator: Zheng, W., Schonemann, R., Aryal, N., Zhou, Q., Rhodes, D., Chiu, Y.-C., Chen, K.-W., Kampert, E., Foerster, T., Martin, T. J., McCandless, G. T., Chan, J. Y., Manousakis, E.,...
Show moreZheng, W., Schonemann, R., Aryal, N., Zhou, Q., Rhodes, D., Chiu, Y.-C., Chen, K.-W., Kampert, E., Foerster, T., Martin, T. J., McCandless, G. T., Chan, J. Y., Manousakis, E., Balicas, L.
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Abstract/Description: We present a detailed quantum oscillatory study on the Dirac type-II semimetallic candidates PdTe2 and PtTe2 via the temperature and the angular dependence of the de Haas-van Alphen and Shubnikov-de Haas effects. In high-quality single crystals of both compounds, i.e., displaying carrier mobilities between 10(3) and 10(4) cm(2)/Vs, we observed a large nonsaturating magnetoresistivity which in PtTe2 at a temperature T = 1.3 K leads to an increase in the resistivity up to (5 x 10(4))% under a...
Show moreWe present a detailed quantum oscillatory study on the Dirac type-II semimetallic candidates PdTe2 and PtTe2 via the temperature and the angular dependence of the de Haas-van Alphen and Shubnikov-de Haas effects. In high-quality single crystals of both compounds, i.e., displaying carrier mobilities between 10(3) and 10(4) cm(2)/Vs, we observed a large nonsaturating magnetoresistivity which in PtTe2 at a temperature T = 1.3 K leads to an increase in the resistivity up to (5 x 10(4))% under a magnetic field mu H-0 = 62 T. These high mobilities correlate with their light effective masses in the range of 0.04 to 1 bare electron mass according to our measurements. For PdTe2 the experimentally determined Fermi surface cross-sectional areas show excellent agreement with those resulting from band structure calculations. Surprisingly, this is not the case for PtTe2, whose agreement between calculations and experiments is relatively poor even when electronic correlations are included in the calculations. Therefore, our study provides strong support for the existence of a Dirac type-II node in PdTe2 and probably also for PtTe2. Band structure calculations indicate that the topologically nontrivial bands of PtTe2 do not cross the Fermi level epsilon(F). In contrast, for PdTe2 the Dirac type-II cone does intersect Bp, although our calculations also indicate that the associated cyclotron orbit on the Fermi surface is located in a distinct k(z) plane with respect to that of the Dirac type-II node. Therefore, it should yield a trivial Berry phase.
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Date Issued: 2018-06-29
Identifier: FSU_libsubv1_wos_000436907600002, 10.1103/PhysRevB.97.235154
Format: Citation

Title: Thallium Isotopes Reveal Protracted Anoxia During The Toarcian (early Jurassic) Associated With Volcanism, Carbon Burial, And Mass Extinction.
Creator: Them, Theodore R., Gill, Benjamin C., Caruthers, Andrew H., Gerhardt, Angela M., Grocke, Darren R., Lyons, Timothy W., Marroquin, Selva M., Nielsen, Sune G., Alexandre, Joao P....
Show moreThem, Theodore R., Gill, Benjamin C., Caruthers, Andrew H., Gerhardt, Angela M., Grocke, Darren R., Lyons, Timothy W., Marroquin, Selva M., Nielsen, Sune G., Alexandre, Joao P. Trabucho, Owens, Jeremy D.
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Abstract/Description: For this study, we generated thallium (TI) isotope records from two anoxic basins to track the earliest changes in global bottom water oxygen contents over the Toarcian Oceanic Anoxic Event (TOAE; similar to 183 Ma) of the Early Jurassic. The T-OAE, like other Mesozoic OAEs, has been interpreted as an expansion of marine oxygen depletion based on indirect methods such as organic-rich facies, carbon isotope excursions, and biological turnover. Our TI isotope data, however, reveal explicit...
Show moreFor this study, we generated thallium (TI) isotope records from two anoxic basins to track the earliest changes in global bottom water oxygen contents over the Toarcian Oceanic Anoxic Event (TOAE; similar to 183 Ma) of the Early Jurassic. The T-OAE, like other Mesozoic OAEs, has been interpreted as an expansion of marine oxygen depletion based on indirect methods such as organic-rich facies, carbon isotope excursions, and biological turnover. Our TI isotope data, however, reveal explicit evidence for earlier global marine deoxygenation of ocean water, some 600 ka before the classically defined T-OAE. This antecedent deoxygenation occurs at the Pliensbachian/Toarcian boundary and is coeval with the onset of initial large igneous province (LIP) volcanism and the initiation of a marine mass extinction. Thallium isotopes are also perturbed during the T-OAE interval, as defined by carbon isotopes, reflecting a second deoxygenation event that coincides with the acme of elevated marine mass extinctions and the main phase of LIP volcanism. This suggests that the duration of widespread anoxic bottom waters was at least 1 million years in duration and spanned early to middle Toarcian time. Thus, the TI data reveal a more nuanced record of marine oxygen depletion and its links to biological change during a period of climatic warming in Earth's past and highlight the role of oxygen depletion on past biological evolution.
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Date Issued: 2018-06-26
Identifier: FSU_libsubv1_wos_000436245000051, 10.1073/pnas.1803478115
Format: Citation

Title: Superconductivity In Fese: The Role Of Nematic Order.
Creator: Kang, Jian, Fernandes, Rafael M., Chubukov, Andrey
Abstract/Description: Bulk FeSe is a special iron-based material in which superconductivity emerges inside a well-developed nematic phase. We present a microscopic model for this nematic superconducting state, which takes into account the mixing between s-wave and d-wave pairing channels and the changes in the orbital spectral weight promoted by the sign-changing nematic order parameter. We show that nematicity only weakly affects T-c, but gives rise to cos 2 theta variation of the pairing gap on the hole pocket,...
Show moreBulk FeSe is a special iron-based material in which superconductivity emerges inside a well-developed nematic phase. We present a microscopic model for this nematic superconducting state, which takes into account the mixing between s-wave and d-wave pairing channels and the changes in the orbital spectral weight promoted by the sign-changing nematic order parameter. We show that nematicity only weakly affects T-c, but gives rise to cos 2 theta variation of the pairing gap on the hole pocket, whose magnitude and size agrees with angle resolved photoemission spectroscopy and STM data. We further show that nematicity increases the weight of the d(xz) orbital on the hole pocket, and increases (reduces) the weight of the d(xy), orbital on the Y (X) electron pocket.
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Date Issued: 2018-06-26
Identifier: FSU_libsubv1_wos_000436558800006, 10.1103/PhysRevLett.120.267001
Format: Citation

Title: Quench Dynamics Across Topological Quantum Phase Transitions.
Creator: Liou, Shiuan-Fan, Yang, Kun
Abstract/Description: We study the dynamics of systems quenched through topological quantum phase transitions and investigate the behavior of the bulk and edge excitations with various quench rates. Specifically, we consider the Haldane model and checkerboard model in slow quench processes with distinct band-touching structures leading to topology changes. The generation of bulk excitations is found to obey the power-law relation Kibble-Zurek and Landau-Zener theories predict. However, an anti-Kibble-Zurek...
Show moreWe study the dynamics of systems quenched through topological quantum phase transitions and investigate the behavior of the bulk and edge excitations with various quench rates. Specifically, we consider the Haldane model and checkerboard model in slow quench processes with distinct band-touching structures leading to topology changes. The generation of bulk excitations is found to obey the power-law relation Kibble-Zurek and Landau-Zener theories predict. However, an anti-Kibble-Zurek behavior is observed in the edge excitations. The mechanism of excitation generation on edge states is revealed, which explains the anti-Kibble-Zurek behavior.
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Date Issued: 2018-06-25
Identifier: FSU_libsubv1_wos_000436192300003, 10.1103/PhysRevB.97.235144
Format: Citation

Title: Topological Phase Transition In A Two-species Fermion System: Effects Of A Rotating Trap Potential Or A Synthetic Gauge Field.
Creator: Liou, Shiuan-Fan, Hu, Zi-Xiang, Yang, Kun
Abstract/Description: We numerically investigate the quantum phases and phase transition in a system made of two species of fermionic atoms that interact with each other via s-wave Feshbach resonance and are subject to rotation or a synthetic gauge field that puts the fermions at Landau level filling factor v(f) = 2. We show that the system undergoes a continuous quantum phase transition from a v(f) = 2 fermionic integer quantum Hall state formed by atoms to a v(b) = 1/2 bosonic fractional quantum Hall state...
Show moreWe numerically investigate the quantum phases and phase transition in a system made of two species of fermionic atoms that interact with each other via s-wave Feshbach resonance and are subject to rotation or a synthetic gauge field that puts the fermions at Landau level filling factor v(f) = 2. We show that the system undergoes a continuous quantum phase transition from a v(f) = 2 fermionic integer quantum Hall state formed by atoms to a v(b) = 1/2 bosonic fractional quantum Hall state formed by bosonic diatomic molecules. In the disk geometry we use, these two different topological phases are distinguished by their different gapless edge excitation spectra, and the quantum phase transition between them is signaled by the closing of the energy gap in the bulk. Comparisons will be made with field-theoretical predictions and the case of p-wave pairing.
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Date Issued: 2018-06-25
Identifier: FSU_libsubv1_wos_000436192800006, 10.1103/PhysRevB.97.245140
Format: Citation

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