The hysteresis loop and switching field in the bilayer film

Abstract

In recent years, some attention has been devoted to composite magnets by combining the best performance of a magnetic material with different anisotropies via exchange coupling. In particular, thin composite films based on magnetic recording have been extensively studied. The case in which one layer with easy-axis anisotropy is coupled to another layer with easy-plane anisotropy is considered. From a theoretical view point, many investigations based on micromagnetic simulation are used to describe a two-phase system. In this paper, the Heisenberg model is utilized to describe a bilayer film system. The magnetization of the system is calculated by the self-consistent effective field theory in an applied magnetic field. The interaction coupling between the soft layer and the hard layer could not be changed, the variation in the ratio of the anisotropies of the bilayer is considered. The hysteresis loop is calculated in an applied field under different directions.