外应力场下铁磁/反铁磁双层膜系统中的自旋波

采用自由能极小的方法研究了铁磁/反铁磁双层膜系统在外应力场下的一致进动自旋波性质，即铁磁共振现象. 本模型中铁磁层很薄可看成单畴结构，但具有单轴磁晶各向异性和立方磁晶各向异性；而反铁磁层仅具有单轴磁晶各向异性，但其厚度趋于半无穷. 推导出了该系统的铁磁共振频率和频谱宽度的解析式. 结果表明，外应力场和界面交换耦合或反铁磁磁强度仅在弱磁场下对系统的铁磁共振有影响，且系统的铁磁共振行为按磁场强度可分为两支，其区分弱磁场和强磁场的临界场依赖于外应力场的方向. 另一方面，应力场方向的改变可借助于反铁磁层磁畴变化对铁磁层磁晶各向异性轴有影响. 关键词： 铁磁/反铁磁双层膜 界面耦合强度 铁磁共振 应力场

Spin waves in ferromagnetic/antiferrmagnetic bilayers under the stress field

Using a method of free energy minimization, the spin wave, namely the ferromagnetic resonance, of ferromagnetic (FM)/antiferromagnetic (AFM) bilayers under the stress field has been investigated. The thin FM film is taken to be a single crystal with cubic or uniaxial magnetocrystalline anisotropy, while the thickness of AFM layer is semi-infinite and has single uniaxial magnetocrystalline anisotropy. Numerical calculation shows that stress field and the interface coupling strength will affect the behavior of FM resonance only under low magnetic field, and there are two branches of FMR modes at the critical field, which distinguishes between the weak and strong external field. The critical field depends on the direction of stress field. On the other hand, the change of the direction of the stress field can weakly affect magnetocrystalline anisotropies axis of FM layer.