Disorder-engineered magnetic compensation in trilayered square Ising ferrimagnet: a Monte Carlo study

In this study, we examine how the thermomagnetic characteristics of spin-1/2 Ising trilayer ferrimagnets made of coupled square monolayers with ABA and AAB stacking sequences are affected by controlled site dilution. The system is composed of two different types of theoretical atoms, with atoms of the same type (A-A and B-B) exhibiting ferromagnetic interactions, while unlike atoms (A-B) display antiferromagnetic interactions. We examine the effects of randomly added nonmagnetic impurities in the A-layers on the system's magnetisation, susceptibility, specific heat, compensation temperature, and critical temperature using comprehensive Metropolis Monte Carlo simulations. The results reveal that increasing impurity concentration systematically, from 5\% to 45\%, lowers both the compensation and critical temperatures, while preserving the continuous nature of the magnetic phase transition, leading to different equilibrium ferrimagnetic behaviours. More importantly, site dilution is found to induce compensation points in regions of the interaction parameter space where compensation is absent in the pristine systems. Comprehensive phase diagrams in the $(J_{AB}/J_{BB} \times J_{AA}/J_{BB})$ plane are constructed for different impurity concentrations, demonstrating the impurity-driven evolution of compensating and non-compensating phases. We further identify threshold impurity concentrations associated with the emergence of magnetic compensation and establish phenomenological scaling relations connecting the compensation characteristics with the interaction strengths and dilution percentage. The phase area in the Hamiltonian parameter space, \textit{without} compensation, scales according to the relation: $\ln |A(\rho)/\tilde{A}|=ae^{b\rho}$, with configuration dependent $a$, $b$, and $\tilde{A}$ .