Phase diagrams of the spin-3/2 random transverse crystal field model

Abstract

The mean-field approximation is used to calculate the phase diagrams of the spin-3/2 random transverse crystal field (RTCF) model. A bimodal distribution of the RTCF is employed in which one of the modes is in competition with the other mode whose strength is adjusted with a controllable parameter α. Thus, some sites in the lattice are under the effect of RTCF D x with probability p and the rest of the sites are under the effect of α D x with 1 − p. The phase diagrams of the model are obtained on the RTCF-temperature planes by varying p on square lattices. Both second-and first-order phase transitions are displayed and thus tricritical points are also observed. The critical end points and end points for the first-order phase transition lines were also found.

Critical behavior of the spin-3/2 Blume Capel quantum model with two random transverse single-ion anisotropies

“…1(a), we have illustrated the pure case (p = 0) where we have obtained the critical temperature of τ = 1.25. This case is in agreement with the reference [29]. The phase diagrams…”

“…Only when 95% of the spins are under the influence of this anisotropy ϕ x the first-order transition appears. This case was treated within another context by E. Albayrak [29] who showed the phase diagram in two dimensions. (a) q = 0, (b) q = 0.50, (c) q = 0.60 and (d) q = 1.0.…”

“…Its effects for the spin-1 models have already been quite investigated [25][26][27]. On the other hand, the spin-3/2 version has not been much explored, only a few works have been published [28,29].The BC model has been explored by several methods, such as, two-spin cluster [30], variational methods [31], constant coupling approximation [32], Monte Carlo simulations [33,35,36,51], finite-size scaling [37][38][39][40], renormalization group methods [41][42][43] and effective field approximation [44][45][46][47].…”

“…In this paper the interest is to study the phase diagram of the BC model with random transverse single-ion anisotropy, i.e., we would like to understand how transverse anisotropy works in the phase diagram topology, and thermodynamic behavior of the spin-3/2 BC model, which were partially treated in Ref. [29]. So we will study the effects of the random transverse single-ion anisotropy (RTSIA) in the phase diagram and the thermodynamic properties of the spin-3/2 BC quantum model.…”