Monte Carlo simulation of exchange bias in spin valve systems

Abstract

We have proposed an atomistic model for the investigation of exchange bias effect in spin valve systems. Using Monte Carlo method, we have studied the field cooled thermal and magnetic properties such as the magnetization, magnetic susceptibility, and specific heat of the system belonging to different regions. Using the cooled spin configuration, we have evaluated the hysteresis loops, and discussed the validity of several theories regarding the physical origin of exchange bias. From our simulations, we have found that, in contrast to spherical particle models, the existence of uncompensated interface spins may not be a sufficient condition for origination of nonzero loop shifts in magnetic multilayers. In other words, a spin valve system with a purely flat interface may not exhibit exchange bias behavior. We have also discussed the influence of interface structure on the aforementioned effect due to a “uniaxial anisotropy” term acting only on the interface spin moments.