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Multistability In An Unusual Phase Diagram Induced By The Competition Between Antiferromagnetic-like Short-range And Ferromagnetic-like Long-range Interactions

Title: Multistability In An Unusual Phase Diagram Induced By The Competition Between Antiferromagnetic-like Short-range And Ferromagnetic-like Long-range Interactions.
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Name(s): Nishino, Masamichi, author
Rikvold, Per Arne, author
Omand, Conor, author
Miyashita, Seiji, author
Type of Resource: text
Genre: Journal Article
Text
Journal Article
Date Issued: 2018-10-02
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: The interplay between competing short-range (SR) and long-range (LR) interactions can cause nontrivial structures in phase diagrams. Recently, horn-shaped unusual structures were found by Monte Carlo simulations in the phase diagram of the Ising antiferromagnet (IA) with infinite-range ferromagnetic-like (F) interactions [Phys. Rev. B 93, 064109 (2016); 96, 174428 (2017)], and also in an IA with LR interactions of elastic origin modeling spin-crossover materials [Phys. Rev. B 96, 144425 (2017)]. To clarify the nature of the phases associated with the horn structures, we study the phase diagram of the IA model with infinite-range F interactions by applying a variational free energy in a cluster mean-field (CMF) approximation. While the simple Bragg-Williams mean-field theory for each sublattice does not produce a horn structure, we find such structures with the CMF method. This confirms that the local thermal fluctuations enabled by the multisite clusters are essential for this phenomenon. We investigate in detail the structure of metastable phases in the phase diagram. In contrast to the phase diagram obtained by the Monte Carlo studies, we find a triple point, at which ferromagnetic-like, antiferromagnetic-like, and disordered phases coexist, and also six tristable regions accompanying the horn structure. We also point out that several characteristic endpoints of first-order transitions appear in the phase diagram. We propose three possible scenarios for the transitions related to the tristable regions. Finally, we discuss the relation between the triple point in this phase diagram and that of a possible lattice-gas model, in which solid, liquid, and gas phases can coexist.
Identifier: FSU_libsubv1_wos_000446296400003 (IID), 10.1103/PhysRevB.98.144402 (DOI)
Keywords: model, field, transition, crystal, polymers, compound, 2-step spin conversion, crossover, molecular material
Publication Note: The publisher’s version of record is available at https://doi.org/10.1103/PhysRevB.98.144402
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_libsubv1_wos_000446296400003
Owner Institution: FSU
Is Part Of: Physical Review B.
2469-9950
Issue: iss. 14, vol. 98

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Nishino, M., Rikvold, P. A., Omand, C., & Miyashita, S. (2018). Multistability In An Unusual Phase Diagram Induced By The Competition Between Antiferromagnetic-like Short-range And Ferromagnetic-like Long-range Interactions. Physical Review B. Retrieved from http://purl.flvc.org/fsu/fd/FSU_libsubv1_wos_000446296400003