Comparative Monte Carlo Study of Magnetic Properties and Compensation Temperature in Cubic and Hexagonal Nanostructure

Abstract

In this paper, we investigate the thermal magnetic properties of two 2D mixed-spin nanostructures, the square SQ-C4S4’3 and the hexagonal HEX-C5S4 geometries, using a systematic Monte Carlo study through the Blume-Capel model. We show that both systems undergo a first-order phase transition from a low-temperature ferrimagnetic state to a high-temperature paramagnetic state, accompanied by a compensation temperature t_comp, at which the total magnetization vanishes. Importantly, the hexagonal structure HEX-C5S4 has better magnetic stability, displaying consistently higher critical transition temperatures (t_r) than the square structure; such critical transition temperature differences between the two lattices have been attributed to the enhanced spin coordination in the hexagonal lattice. Besides, we show here that the increase in exchange interactions raises both t_comp and t_r significantly, the crystalline field δ has affected only t_comp, and the external magnetic field h suppresses the latter and slightly decreases t_r. Finally, we conclude that the results have given unambiguous evidence that symmetry and the topology of the lattice represent two crucial design parameters, which fundamentally determine the magnetic stability and the characteristics of thermal phase transition of the mixed-spin nanostructures.