Phase transition in spin systems with various types of fluctuations

Miyashita, Seiji

doi:10.2183/pjab.86.643

Cited by 19 publications

(19 citation statements)

References 192 publications

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“…A 1/3 Néel phase with fixed magnetization separates the two co-planar phases. The phase transition to the saturated phase occurs exactly at B = 3(J z + J/2) as for the classical triangular antiferromagnet [21][22][23][24][25].Our results also show several differences to the previous study [25]: 1.) The so-called π-coplanar phase is missing.…”

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confidence: 39%

Phase diagram of the antiferromagnetic XXZ model on the triangular lattice

2015

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We determine the quantum phase diagram of the antiferromagnetic spin-1/2 XXZ model on the triangular lattice as a function of magnetic field and anisotropic coupling Jz. Using the density matrix renormalization group (DMRG) algorithm in two dimensions we establish the locations of the phase boundaries between a plateau phase with 1/3 Néel order and two distinct coplanar phases. The two coplanar phases are characterized by a simultaneous breaking of both translational and U(1) symmetries, which is reminiscent of supersolidity. A translationally invariant umbrella phase is entered via a first order phase transition at relatively small values of Jz compared to the corresponding case of ferromagnetic hopping and the classical model. The phase transition lines meet at two tricritical points on the tip of the lobe of the plateau state, so that the two coplanar states are completely disconnected. Interestingly, the phase transition between the plateau state and the upper coplanar state changes from second order to first order for large values of Jz > ∼ 2.5J.PACS numbers: 75.10. Jm, 67.80.kb, 05.30.Jp Competing interactions between quantum spins can prevent conventional magnetic order at low temperatures. In the search of interesting and exotic quantum phases frustrated systems are therefore at the center of theoretical and experimental research in different areas of physics . One of the most straight-forward frustrated system is the spin-1/2 antiferromagnet (AF) on the triangular lattice, which was also the first model to be discussed as a potential candidate for spin-liquid behavior without conventional order by Anderson [2]. It is now known that the isotropic Heisenberg model on the triangular lattice is not a spin liquid and does show order at zero temperature [3]. Nonetheless, the phase diagram as a function of magnetic field is still actively discussed with recent theoretical calculations [4,5] as well as experimental results [6-9] on Ba 3 CoSb 2 O 9 , which appears to be very well described by a triangular AF. Interesting phases have also been found for anisotropic triangular lattices [11][12][13] and for the triangular extended Hubbard model [14]. Hard-core bosons with nearest neighbor interaction on a triangular lattice correspond to the xxz model with ferromagnetic exchange in the xy-plane, which has been studied extensively [15][16][17][18][19][20]. In this case a so-called supersolid phase near half-filling has been established for large interactions [15], which is characterized by two order parameters, namely a superfluid density and a √ 3 × √ 3 charge density order. Impurity effects show that the two order parameters are competing [17] and the transition to the superfluid state is first order [19,20].However, surprisingly little attention has been paid to the role of an antiferromagnetic anisotropic exchange interaction away from half-filling [24][25][26][27], even though the XXZ model on the triangular lattice H = J ij (Ŝ x iŜ x j +Ŝ y iŜ y j ) + J z ij Ŝ z iŜ z j − B iŜ z i , (1) is arguable one of the...

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confidence: 39%

Phase diagram of the antiferromagnetic XXZ model on the triangular lattice

2015

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“…As E st tends to rotate the molecules and align their polarization vectors, it also alters their positions because molecules have a given shape and rotating them conflicts with steric constraints: E st thus corresponds to a new constraint unfavorable to dynamical correlations, i.e., it slows down the dynamics, hence the increase of T g with E st . More generally, a static field gives rise to subtle effects strongly dependent of the kind of frustrated system which is considered: in the very specific case of spin glasses, the critical temperature may decrease with the static (magnetic) field (although this is strongly debated [33][34][35][36]), while in other systems reentrant behaviors at very high fields may happen [37]. Some further work is in progress to study the behavior of δT g (E st ) at higher values of the static field.…”

Section: A Physical Picturementioning

confidence: 99%

Control parameter for the glass transition of glycerol evidenced by the static-field-induced nonlinear response

et al. 2014

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International audienceBy studying a nonlinear susceptibility on supercooled glycerol, we show that applying a static field E st increases the glass transition temperature T g by an amount quadratic in E st. This has important consequences: (i) it reinforces the relation between the two paths put forward in the last years to unveil the dynamical correlation volume close to T g ; (ii) it clarifies the interpretation of nonlinear measurements; (iii) it yields a new control parameter of the glass transition, which paves the way for experiments deepening our understanding of glasses

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“…With added next-nearest-neighbor (NNN) FM interaction, both the three-state AFM Potts model 42 and the TAFI model [43][44][45][46] are known to have BKT-type phase transitions in the same universality class as the six-state clock model [47][48][49] . Under simple transformation the sixstate clock model is mapped to the TAFI model 46 .…”

Section: Introductionmentioning

confidence: 99%

“…Under simple transformation the sixstate clock model is mapped to the TAFI model 46 . The six-state model can exhibit either a first-order transition, two BKT-type transitions, or successive Ising, three-state Potts, or Ashkin-Teller-type transitions 50 .…”

Section: Introductionmentioning

confidence: 99%

Phase transition properties of the Bell-Lavis model

2014

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Using Monte Carlo calculations we analyze the order and the universality class of phase transitions into a low density (honeycomb) phase of a triangular antiferromagnetic three-state Bell-Lavis model. The results are obtained in a whole interval of chemical potential µ corresponding to the honeycomb phase. Our results demonstrate that the phase transitions might be attributed to the three-state Potts universality class for all µ values except for the edges of the honeycomb phase existence. At the honeycomb phase and the low density gas phase boundary the transitions become of the first order. At another, honeycomb-to-frustrated phase boundary, we observe the approach to the crossover from the three-state Potts to the Ising model universality class. We also obtain the Schottky anomaly in the specific heat close to this edge. We show that the intermediate planar phase, found in a very similar antiferromagnetic triangular Blume-Capel model, does not occur in the Bell-Lavis model.

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Phase transition in spin systems with various types of fluctuations

Cited by 19 publications

References 192 publications

Phase diagram of the antiferromagnetic XXZ model on the triangular lattice

Phase diagram of the antiferromagnetic XXZ model on the triangular lattice

Control parameter for the glass transition of glycerol evidenced by the static-field-induced nonlinear response

Phase transition properties of the Bell-Lavis model

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