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 Title
 Possible Nematic Spin Liquid In Spin1 Antiferromagnetic System On The Square Lattice: Implications For The Nematic Paramagnetic State Of Fese.
 Creator

Gong, ShouShu, Zhu, W., Sheng, D. N., Yang, Kun
 Abstract/Description

The exotic normal state of iron chalcogenide superconductor FeSe, which exhibits vanishing magnetic order and possesses an electronic nematic order, triggered extensive explorations of its magnetic ground state. To understand its novel properties, we study the ground state of a highly frustrated spin1 system with bilinearbiquadratic interactions using an unbiased largescale density matrix renormalization group. Remarkably, with increasing biquadratic interactions, we find a paramagnetic...
Show moreThe exotic normal state of iron chalcogenide superconductor FeSe, which exhibits vanishing magnetic order and possesses an electronic nematic order, triggered extensive explorations of its magnetic ground state. To understand its novel properties, we study the ground state of a highly frustrated spin1 system with bilinearbiquadratic interactions using an unbiased largescale density matrix renormalization group. Remarkably, with increasing biquadratic interactions, we find a paramagnetic phase between Neel and stripe magnetic ordered phases. We identify this phase as a candidate of nematic quantum spin liquid by the compelling evidences, including vanished spin and quadrupolar orders, absence of lattice translational symmetry breaking, and a persistent nonzero lattice nematic order in the thermodynamic limit. The established quantum phase diagram naturally explains the observations of enhanced spin fluctuations of FeSe in neutron scattering measurement and the phase transition with increasing pressure. This identified paramagnetic phase provides a possibility to understand the novel properties of FeSe.
Show less  Date Issued
 20170519
 Identifier
 FSU_libsubv1_wos_000401654300004, 10.1103/PhysRevB.95.205132
 Format
 Citation
 Title
 Variational Monte Carlo Study Of Chiral Spin Liquid In Quantum Antiferromagnet On The Triangular Lattice.
 Creator

Hu, WenJun, Gong, ShouShu, Sheng, D. N.
 Abstract/Description

By using Gutzwiller projected fermionic wave functions and variational Monte Carlo technique, we study the spin1/2 Heisenberg model with the firstneighbor (J(1)), secondneighbor (J(2)), and additional scalar chiral interaction J(chi)S(i) . (Sj x Sk) on the triangular lattice. In the nonmagnetic phase of the J(1)J(2) triangular model with 0.08 less than or similar to J(2)/J(1) less than or similar to 0.16, recent densitymatrix renormalization group (DMRG) studies [Zhu and White, Phys....
Show moreBy using Gutzwiller projected fermionic wave functions and variational Monte Carlo technique, we study the spin1/2 Heisenberg model with the firstneighbor (J(1)), secondneighbor (J(2)), and additional scalar chiral interaction J(chi)S(i) . (Sj x Sk) on the triangular lattice. In the nonmagnetic phase of the J(1)J(2) triangular model with 0.08 less than or similar to J(2)/J(1) less than or similar to 0.16, recent densitymatrix renormalization group (DMRG) studies [Zhu and White, Phys. Rev. B 92, 041105(R) (2015) and Hu, Gong, Zhu, and Sheng, Phys. Rev. B 92, 140403(R) (2015)] find a possible gapped spin liquid with the signal of a competition between a chiral and a Z(2) spin liquid. Motivated by the DMRG results, we consider the chiral interaction J(chi)S(i) . (Sj x Sk) as a perturbation for this nonmagnetic phase. We find that with growing J(chi), the gapless U(1) Dirac spin liquid, which has the best variational energy for J(chi) = 0, exhibits the energy instability towards a gapped spin liquid with nontrivial magnetic fluxes and nonzero chiral order. We calculate topological Chern number and groundstate degeneracy, both of which identify this flux state as the chiral spin liquid with fractionalized Chern number C = 1/2 and twofold topological degeneracy. Our results indicate a positive direction to stabilize a chiral spin liquid near the nonmagnetic phase of the J(1)J(2) triangular model.
Show less  Date Issued
 20160815
 Identifier
 FSU_libsubv1_wos_000381482600002, 10.1103/PhysRevB.94.075131
 Format
 Citation
 Title
 Emergent Quasionedimensionality In A Kagome Magnet: A Simple Route To Complexity.
 Creator

Gong, ShouShu, Zhu, Wei, Yang, Kun, Starykh, Oleg A., Sheng, D. N., Balents, Leon
 Abstract/Description

We study the groundstate phase diagram of the quantum spin1/2 Heisenberg model on the kagome lattice with first(J(1) < 0), second(J(2) < 0), and thirdneighbor interactions (J(d) > 0) by means of analytical lowenergy field theory and numerical densitymatrix renormalization group (DMRG) studies. The results offer a consistent picture of the J(d)dominant regime in terms of three sets of spin chains weakly coupled by the ferromagnetic interchain interactions J(1,2). When either J(1) or J...
Show moreWe study the groundstate phase diagram of the quantum spin1/2 Heisenberg model on the kagome lattice with first(J(1) < 0), second(J(2) < 0), and thirdneighbor interactions (J(d) > 0) by means of analytical lowenergy field theory and numerical densitymatrix renormalization group (DMRG) studies. The results offer a consistent picture of the J(d)dominant regime in terms of three sets of spin chains weakly coupled by the ferromagnetic interchain interactions J(1,2). When either J(1) or J(2) is much stronger than the other one, the model is found to support one of two cuboctohedral phases, cuboc1, and cuboc2. These cuboc states host noncoplanar longranged magnetic order and possess finite scalar spin chirality. However, in the compensated regime J(1) similar or equal to J(2), a valence bond crystal phase emerges between the two cuboc phases. We find excellent agreement between an analytical theory based on coupled spin chains and unbiased DMRG calculations, including at a very detailed level of comparison of the structure of the valence bond crystal state. To our knowledge, this is the first such comprehensive understanding of a highly frustrated twodimensional quantum antiferromagnet. We find no evidence of either the onedimensional gapless spin liquid or the chiral spin liquids, which were previously suggested by parton meanfield theories.
Show less  Date Issued
 20160727
 Identifier
 FSU_libsubv1_wos_000381482700001, 10.1103/PhysRevB.94.035154
 Format
 Citation
 Title
 Interactiondriven Fractional Quantum Hall State Of Hardcore Bosons On Kagome Lattice At Onethird Filling.
 Creator

Zhu, W., Gong, S. S., Sheng, D. N.
 Abstract/Description

There has been a growing interest in realizing topologically nontrivial states of matter in band insulators, where a quantum Hall effect can appear as an intrinsic property of the band structure. While ongoing progress is under way with a number of directions, the possibility of realizing novel interactiongenerated topological phases, without the requirement of a nontrivial invariant encoded in singleparticle wave function or band structure, can significantly extend the class of topological...
Show moreThere has been a growing interest in realizing topologically nontrivial states of matter in band insulators, where a quantum Hall effect can appear as an intrinsic property of the band structure. While ongoing progress is under way with a number of directions, the possibility of realizing novel interactiongenerated topological phases, without the requirement of a nontrivial invariant encoded in singleparticle wave function or band structure, can significantly extend the class of topological materials and is thus of great importance. Here, we show an interactiondriven topological phase emerging in an extended BoseHubbard model on a kagome lattice, where the noninteracting band structure is topological trivial with zero Berry curvature in the Brillouin zone. By means of an unbiased stateoftheart densitymatrix renormalization group technique, we identify that the ground state in a broad parameter region is equivalent to a bosonic fractional quantum Hall Laughlin state, based on the characterization of universal properties including groundstate degeneracy, edge excitations, and anyonic quasiparticle statistics. Our work paves a way to finding an interactioninduced topological phase at the phase boundary of conventionally ordered solid phases.
Show less  Date Issued
 20160713
 Identifier
 FSU_libsubv1_wos_000379502800001, 10.1103/PhysRevB.94.035129
 Format
 Citation