The Effect Of External Stress On The Ferromagnetic/Antiferromagnetic Exchang Bias Systems

Various giant magnetoresistance devices are widely applied in the mechanical and electrical, automotive and high-density information storage areas, since the giant magnetoresistance (GMR) effect is discovered. It is very important to investigate the ferromagnetic (FM)/antiferromagnetic (AFM) exchange bias in the usage of giant magnetoresistance devices. The reason of jump phenomenon occured in the angular dependence of the exchange bias of FM/AFM systems has been explained theoretically, and it is found that the external stress is a valid way to control and tune the exchange bias of FM/AFM systems. When the uniaxial anisotropy and the exchange anisotropy are perpendicular, using the principle of the minimum energy and the Stoner-Wohlfarth model, we have mainly studied the effects of the orientation and the magnitude of applied stress on the exchange bias magnetization reversal and the angular dependence relation of FM/AFM systems under considering the following aspects, i.e., uniaxial anisotropy, exchange anisotropy, and external stress. This study may provide a theoretical basis to better receive the largest exchange bias field and the coercivity field for optimizing the relevant devices. The numerical results indicate that there are transitions between the monostable state and the bistable state of the FM/AFM systems, and prominent changes in the angular dependence of exchange bias. When the FM/AFM systems are in the monostable state, only four jumps appear in the curves of the exchange bias field and coercivity field; and eight jumps appear when it is in the bistable state. The variational trend of the curves for the angular dependence relation shows distinct differences in comparison to the case of the uniaxial anisotropy and exchange anisotropy parallelled if the orientation of applied stress is changed. With the angle of the applied stress increasing, the vibrational behavior of the exchange bias field becomes much stronger, and its amplitude therewith changes.