摘要
采用能量极小原理及Stoner-Wohlfarth模型,研究了张应力对铁磁/反铁磁双层薄膜交换偏置的影响。在不施加外磁场时,根据体系能量与铁磁层磁化强度方向之间的关系,得到了内禀易轴与内禀难轴的位置。交换各向异性与单轴各向异性之间的竞争使体系存在单稳态与双稳态两种不同的状态,直接决定了交换偏置的角度依赖关系。分析磁化过程发现,外磁场在沿内禀易轴及内禀难轴方向施加时,磁滞回线的一支转换场发生突变,另一支转换场保持不变,最终导致交换偏置场和矫顽场出现阶跃行为。在阶跃点处,体系具有较大的交换偏置场和矫顽场。数值计算表明:张应力的大小与方向对交换偏置均有很大的影响,均可以使体系在单稳态与双稳态之间相互转变并导致角度依赖关系发生显著变化。研究表明,应力可作为一种可行的方法来控制和调节铁磁/反铁磁体系的交换偏置。
Based on the principle of minimal energy and Stoner-Wohlfarth model,the effect of the tensile stress on the exchange bias for ferromagnetic/antiferromagnetic 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 location of the intrinsic easy axes and intrinsic hard axes of the system have been obtained.It is found that the system will be in monostable state or bistable state,which is controlled by the competition between the uniaxial anisotropy and the exchange anisotropy of the system.Monostable state and bistable state of the system determine the angular dependence of exchange bias immediately.When the applied field is parallel to the intrinsic easy axes and intrinsic hard axes,by analyzing the magnetization process,we find that one of the switching field of the hysteresis loop shows a jump,while the other is kept constant,and consequently the exchange bias field and the coercivity will appear a step.Both the exchange bias field and the coercivity have a greater value at the point of step.The numerical calculations indicate that both the magnitude and the orientation of the tensile 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 tensile stress is a viable way to control and tune the exchange bias of the ferromagnetic/antiferromagnetic bilayers.
出处
《高压物理学报》
EI
CAS
CSCD
北大核心
2009年第4期252-260,共9页
Chinese Journal of High Pressure Physics
基金
国家自然科学基金(10762001)
教育部新世纪优秀人才计划基金(NCET-2005-0272)
高等学校博士学科点专项科研基金(200801260003)
关键词
单稳态
双稳态
张应力
内禀易轴
内禀难轴
monostable state
bistable state
tensile stress
intrinsic easy axis
intrinsic hard axis
