Effect of applied stress on exchange bias in ferromagnetic/antiferromagnetic bilayers and the phenomenon of the jump

Abstract

Using the principle of minimal energy and S-W model，the effect of the applied stress on exchange bias in ferromagnetic （FM） / antiferromagnetic （AFM） bilayers has been investigated.When the applied field is absent，according to the relation between the energy of the system and the orientation of ferromagnetic magnetization， the system will be in monostable state or bistable state，which is controlled by the competition between the uniaxial anisotropy and the exchange anisotropy.Monostable state or bistable state of the system determine the angular dependence of exchange bias immediately.When the external field is applied along the intrinsic easy axes and intrinsic hard axes， it is found by analyzing the magnetization processes that one of the switching field of the hysteresis loop shows a an abrupt change，while the other is kept constant，and consequently the exchange bias field and the coercivity will appear a jump phenomenon.The numerical calculations indicate that both the exchange bias field and the coercivity are larger in the magnitude at the points of the jump.Both the magnitude and the orientation of the applied stress will significantly affect the exchange bias by making a transition between monostable state and bistable state in the system.This transition induces a significant change in angular dependence of the exchange bias. Our results demonstrate that the applied stress is a viable way to control and tune the exchange bias of the FM/AFM bilayers.