双二次耦合场对铁磁/反铁磁双层膜中交换偏置场的影响

Effect of Biquadratic Coupling on Exchange Bias of Ferromagnetic and Antiferromagnetic Bilayer Films

研究了界面双线性耦合和双二次耦合对铁磁/反铁磁双层膜中交换偏置场的影响.结果表明:随着双线性耦合场或双二次耦合场的增加,交换偏置场的最大值位置向易轴靠近.另外,交换偏置场随外磁场角度的变化曲线随着双二次耦合场的增加,逐渐趋于正弦图像.其根源在于双二次耦合场与铁磁层单轴各向异场二者作用相互抵消,使曲线趋于光滑.铁磁层的磁滞回线对双二次耦合场也有一定的依赖.

The effects of bilinear and biquadratic terms on exchange bias of ferromagnetic and antiferromagnetic bilayer films are investigated. The results show that the maximum of the exchange bias field departs from easy axis with increasing the biquadratic-coupling field or bilinear field. In addition, the angular dependence of exchange bias gradually becomes the sine function with increasing the biquadratic-coupling field. The reason is that the effects of biquadratic-coupling field and uniaxial anisotropy of the ferromagnetic counteract each other to smooth the curves gradually. The hysteresis loops also depends on the biquadratic term.