Angular Dependence of the Exchange Bias with the Uniaxial Anisotropy Perpendicular to the Unidirectional Anisotropy

Based on the principle of minimal energy, the angular dependence of exchange bias has been investigated with the uniaxial anisotropy perpendicular to the unidirectional anisotropy in ferromagnetic/antiferromagnetic bilayers. The competition between unidirectional and uniaxial anisotropies divides the initial magnetization state of the bilayer into monostable state and bistable state, which determine the angular dependence directly. By analyzing the magnetization reversal processes, one of the coercive fields of the hysteresis loop shows a discontinuity while the other is kept continuous at the orientation angles of the intrinsic easy axes, which induces a jump phenomenon in the curves of the angular dependence of the exchange bias. It is found that this jump phenomenon is an intrinsic property of the bilayers.