Phase Transitions in Frustrated Metamagnets

Abstract

Phase diagrams and magnetic properties of the frustrated metamagnets have been studied. We have shown that strong disorder can narrow the temperature and the magnetic-field interval where the metamagnetic transition takes place. With increasing disorder this discontinuous transition disappears transforming into the second-order phase transition. The magnetic field usually widens the region of the (H, T) phase diagram where the antiferromagnetic nonergodic state exists. The de Almeida-Thouless line has a jump when crossing the metamagnetic phase transition line which results in discontinuous transition into the nonergodic state.

Stability of a two-sublattice spin-glass model

“…Therefore the equation determining line (a) is which is in agreement with previous study [12]. The P solution is T unstable below line (b).…”

“…The P phase becomes T unstable below line (b), and AF phase below line (c). Notice that the lines (b) and (c) are discontinuous across first-order transition [12]. It is likely that the first-order transition line will change in this part of phase diagram once the replicasymmetry-breaking solutions are considered for P and AF phases.…”

Replica symmetry breaking in bipartite spin glasses and neural networks

“…We considered N = 400 spins and 31 different values of α h = N h /N uniformly distributed from 0.125 to 0.875. 15 In order to compute the 14 Note that the RSB-1 calculation assumes the N → ∞ limit while the MC and graph partitioning simulations necessarily incorporate finite-size effects, so the methods would produce slightly different results even if the numerical simulations were perfectly accurate. 15 The all-to-all nature of the bipartite couplings results in far more bonds than are present in a local system with the same number of spins.…”

Two-sublattice fermionic Ising spin glass model in a transverse field: Asymmetric replica symmetry breaking solution

“…In this context, the interplay between disorder and magnetic fields (H, GÞ in the SG/AF competition is analyzed. Therefore, model is given by Hamiltonian [7] The spin operators in Eq. (1) are defined in terms of fermion operators as in Ref.…”