Magnon Bose-Einstein condensation and various phases of three-dimensonal quantum helimagnets under high magnetic field

Ueda, Hiroaki; Totsuka, Keisuke

doi:10.1103/physrevb.80.014417

Cited by 69 publications

(119 citation statements)

References 41 publications

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“…[44][45][46][47][48] In this way, magnetically ordered phases just below saturation (h = h sat − δh) can be understood as a BEC instability of the ground state just above saturation (h = h sat + δh). This limit has the advantage of allowing one to incorporate all of the competing effects of interest-quantum fluctuations, DM coupling, and spatial anisotropy-in a single controlled and coherent framework.…”

Section: Bose-einstein Condensation Analysis Near Saturationmentioning

confidence: 99%

Deformed triangular lattice antiferromagnets in a magnetic field: Role of spatial anisotropy and Dzyaloshinskii-Moriya interactions

et al. 2011

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Recent experiments on the anisotropic spin-1/2 triangular antiferromagnet Cs 2 CuBr 4 have revealed a remarkably rich phase diagram in applied magnetic fields, consisting of an unexpectedly large number of ordered phases. Motivated by this finding, we study the role of three ingredients-spatial anisotropy, Dzyaloshinskii-Moriya interactions, and quantum fluctuations-on the magnetization process of a triangular antiferromagnet, coming from the semiclassical limit. The richness of the problem stems from two key facts: (1) the classical isotropic model with a magnetic field exhibits a large accidental ground-state degeneracy and (2) these three ingredients compete with one another and split this degeneracy in opposing ways. Using a variety of complementary approaches, including extensive Monte Carlo numerics, spin-wave theory, and an analysis of Bose-Einstein condensation of magnons at high fields, we find that their interplay gives rise to a complex phase diagram consisting of numerous incommensurate and commensurate phases. Our results shed light on the observed phase diagram for Cs 2 CuBr 4 and suggest a number of future theoretical and experimental directions that will be useful for obtaining a complete understanding of this material's interesting phenomenology.

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Section: Bose-einstein Condensation Analysis Near Saturationmentioning

confidence: 99%

Deformed triangular lattice antiferromagnets in a magnetic field: Role of spatial anisotropy and Dzyaloshinskii-Moriya interactions

et al. 2011

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“…To determine this structure, we construct an effective model. The lowest energy magnon excitations in the triangular lattice occur at nonzero momenta ±Q, which minimize the dispersion 23,24 . In our (sheared) coordinates, the dispersion relation is…”

Section: B Effective Field Theory For Dilute Bosonsmentioning

confidence: 99%

“…To formalize the magnon BEC picture, one may transform the spin model to a bosonic one [20][21][22][23][24][25] , using the equivalence of the spin s = 1/2 Hilbert space to that of hard-core bosons:…”

Section: A Spin Flip Bosonsmentioning

confidence: 99%

Ground states of spin-12triangular antiferromagnets in a magnetic field

Chen

Jiang

et al. 2013

Phys. Rev. B

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We use a combination of numerical density matrix renormalization group (DMRG) calculations and several analytical approaches to comprehensively study a simplified model for a spatially anisotropic spin-1/2 triangular lattice Heisenberg antiferromagnet: the three-leg triangular spin tube (TST). The model is described by three Heisenberg chains, with exchange constant J, coupled antiferromagnetically with exchange constant J along the diagonals of the ladder system, with periodic boundary conditions in the shorter direction. Here we determine the full phase diagram of this model as a function of both spatial anisotropy (between the isotropic and decoupled chain limits) and magnetic field. We find a rich phase diagram, which is remarkably dominated by quantum states -the phase corresponding to the classical ground state appears only in an exceedingly small region. Among the dominant phases generated by quantum effects are commensurate and incommensurate coplanar quasi-ordered states, which appear in the vicinity of the isotropic region for most fields, and in the high field region for most anisotropies. The coplanar states, while not classical ground states, can at least be understood semiclassically. Even more strikingly, the largest region of phase space is occupied by a spin density wave phase, which has incommensurate collinear correlations along the field. This phase has no semiclassical analog, and may be ascribed to enhanced one-dimensional fluctuations due to frustration. Cutting across the phase diagram is a magnetization plateau, with a gap to all excitations and "up up down" spin order, with a quantized magnetization equal to 1/3 of the saturation value. In the TST, this plateau extends almost but not quite to the decoupled chains limit. Most of the above features are expected to carry over to the two dimensional system, which we also discuss. At low field, a dimerized phase appears, which is particular to the one dimensional nature of the TST, and which can be understood from quantum Berry phase arguments.

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“…53 for a recent study of helical order in a 3D magnet in high magnetic fields͒ while the SDW instability in the high-field region would turn the highfield region into a collinear, magnetically ordered state with long-range incommensurate ͗S z ͑x͒S z ͑0͒͘ correlations. The former conclusion ͑a helical phase in the low-field region͒ is in agreement with the available experimental data 30,34,35 while the latter conjecture of collinear incommensurate order could be tested by neutron-scattering experiments and is consistent with the nuclear-magnetic-resonance measurements 35,36 suggesting that the magnetic order becomes collinear in applied fields above Ϸ7.5 T. It should be mentioned that a similar incommensurate collinear structure has been recently observed 54 in the quasi-1D material BaCo 2 V 2 O 8 with easy-axis anisotropy.…”

Section: Discussionmentioning

confidence: 99%

Phase diagram of an anisotropic frustrated ferromagnetic spin-12chain in a magnetic field: A density matrix renormalization group study

2009

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We study the phase diagram of a frustrated spin-1 2 ferromagnetic chain with anisotropic exchange interactions in an external magnetic field using the density matrix renormalization group method. We show that an easy-axis anisotropy enhances the tendency toward multimagnon bound states while an easy-plane anisotropy favors chirally ordered phases. In particular, a moderate easy-plane anisotropy gives rise to a quantum phase transition at intermediate magnetization. We argue that this transition is related to the finite-field phase transition experimentally observed in the spin-1 2 compound LiCuVO 4 .

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Magnon Bose-Einstein condensation and various phases of three-dimensonal quantum helimagnets under high magnetic field

Cited by 69 publications

References 41 publications

Deformed triangular lattice antiferromagnets in a magnetic field: Role of spatial anisotropy and Dzyaloshinskii-Moriya interactions

Deformed triangular lattice antiferromagnets in a magnetic field: Role of spatial anisotropy and Dzyaloshinskii-Moriya interactions

Ground states of spin-12triangular antiferromagnets in a magnetic field

Phase diagram of an anisotropic frustrated ferromagnetic spin-12chain in a magnetic field: A density matrix renormalization group study

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