双层亚铁磁性超晶格的零温磁矩

Zero temperature magnetic moment of double-layer ferrimagnetic superlattices

采用海森堡模型,利用线性自旋波近似、傅立叶变换和格林函数技术对双层亚铁磁超晶格进行理论研究,推导出零温磁矩表达式,分析了系统的各个参数(自旋量子数、层间交换耦合系数、层内交换耦合系数、外磁场及各向异性参数)对系统零温磁矩的影响.结果表明,系统的各个参数对系统零温磁矩有重要影响;系统的零温磁矩随层内交换耦合系数、各向异性参数的增加而增加,随层间交换耦合系数的增加而先增加后减小.当两层的自旋量子数S1,S2相等时,两条零温磁矩曲线重合;相反,当两层的自旋量子数S1,S2不等时,两条零温磁矩曲线分开.

Theoretical studies of double-layer ferrimagnetic superlattices were conducted with Heisenberg model, linear spin wave approximation, Fourier transformation and Green function technology. The expressions of zero temperature magnetic moment were calculated. The influences of the system parameters such as spin quantum number, interlayer exchange couplings, intralayer exchange couplings, external magnetic field and anisotropy constant on zero temperature magnetic moment were analyzed. The result shows that the system parameters have important effect on zero temperature magnetic moment. It has been found that zero temperature magnetic moment increases with increasing the intralayer exchange couplings and anisotropy constant, while firstly increases and then decreases with increasing the interlayer exchange couplings when the spin quantum numbers of the double layers are same, the curves of two branches of zero temperature magnetic moment are superposition. Contrarily, when the spin quantum numhers of the double layers are different, the curves of two branches of zero temperatue magnetic moment are detached.