Compensation temperature in spin-1∕2 Ising trilayers: A Monte Carlo study

Abstract

We study the magnetic and thermodynamic properties of a spin-1/2 Ising system containing three layers, each of which is composed exclusively of one out of two possible types of atoms, A or B. The A-A and B-B bonds are ferromagnetic while the A-B bonds are antiferromagnetic. The study is performed through Monte Carlo simulations using the Wolff algorithm and the data are analyzed with the aid of the multiple-histogram reweighting technique and finite-size scaling tools. We verify the occurrence of a compensation phenomenon and obtain the compensation and critical temperatures of the model as functions of the Hamiltonian parameters. The influence of each parameter on the overall behavior of the system is discussed in detail and we present our results in the form of phase diagrams dividing the parameter space in regions where the compensation phenomenon is present or absent. Our results may provide invaluable information for experimentalists seeking to build materials with desired characteristics. *

Thermodynamic behaviour of magnetocaloric quantities in spin-1/2 Ising square trilayer

“…-17 shows the phase seperation curves obtained for two types of configurations under our valid ranges of observations which agree fairly well with [24] where the curves are obtained via MFA, EFA and MC simulations.…”

“…The model described above was simulated using the Monte Carlo simulations with Metropolis single spin-flip algorithm [50,51] with each plane having L 2 sites with a system size having L = 100. For L 60 compensation point tends to a stable value [24], thus the lattice size in our study is quite standard. The initial high temperature paramagnetic phase of spin configurations had randomly selected 50% of total number of spins in upward projection with S i = +1 and the rest in downward projection with S i = −1 (Using 1 instead of 1/2 rescales the coupling constants only).…”

“…We consider, in this study, an Ising superlattice containing three magnetic layers on square lattice with the following details (as in [23,24]): The equilibrium spin configuration on any layer is determined by the condition that the free energy of the whole system should be a minimum. As we've considered the spins to interact Ising-like, in-plane as well as out-of-plane, the Hamiltonian for the trilayer system is:…”

“…Because of a limited number of exact methods available, approximate and numerical studies have their own importance. Referring to recent studies on layered magnetism in the literature, it is reported, by MFA and EFA in [23] and by MC simulations with Single cluster Wolff Algorithm in [24] that under certain range of different types of interaction strengths between lattice sites, different temperature dependencies of sublattice magnetisations cause the compensation point to appear in an Ising trilayer on square lattice. A quasi three-dimensional, spin-1/2, Ising trilayer stacking on square lattice with quenched non-magnetic impurity is studied in [44] and it is observed, the critical and compensation points, can be modulated to drift towards lower temperatures with increasing concentration of non-magnetic impurities and in [45], it was hinted that reduced residual magnetisation, another magnetocaloric quantity, possibly varies in a systematic way.…”

“…For layered single-spin systems having even number of layers, necessity of site dilution and strict restrictions on the conditions of controlling parameters for the occurence of compensation effect has been verified through pair approximation (PA) calculations [18,19] for the Ising-Heisenberg systems and by MC simulations for the Ising systems [20,21]. But for odd number of layers, neither cite dilution [22] nor mixed-spin cases [23,24] are necessary for observing compensation. That is why our area of interest in this article is compensation point, T comp , of the trilayered spin-1/2 Ising ferrimagnet.…”