Magnetic properties of mixed spin Ising system with modified surface-bulk coupling: Monte Carlo treatment

Abstract

A Monte Carlo simulation is used to study the three dimensional mixed spin-½ and spin-1 Ising model with intrasurface J_S and surface-bulk J_^ interactions modified with respect to the bulk exchange interaction JB. In this investigation, the new parameter J_^ strongly affects the phase diagram obtained in the case J_^ = JB. We have found three types of phase diagrams which show some qualitatively interesting features, i.e. variety of phase transitions and multicritical points. One of the most qualitatively interesting features of the surface is the existence of two possible ferrimag-netic orderings, when the ratio R1 = J_^/JB belongs to an appropriate range. A compensation point in the surface magnetization is found when the ratio of the surface and bulk exchange interactions belong to certain ranges. This phenomenon may have important applications in technology such as thermodynamic writing and erasing at the compensation point. Comparison between Monte Carlo results and those obtained by mean field theory is also made.