Abstract: Monte Carlo method is used to study hysteresis loops of FM/AFM systems with FM core embedded in an AFM matrix in a classical Heisenberg model. Magnetocrystalline anisotropy and exchange interaction are considered. It indicates that the shape of hysteresis loops changes with reverse maximal external field. The magnetization shows a jumping transition to metastable equilibrium with an increasing of external fields along positive z axis. The jumping range is independent of reverse maximal external field. With an increasing of AFM magnetocrystalline anisotrepy, exchange bias is obvious and larger external fields are needed for magnetization saturation. With an increasing of AFM exchange interaction, new hysteresis loops may appear in positive and negative external fields.

Key words: FM/AFM, Monte Carlo method, hysteresis loop, exchange bias