侧向铁磁/铁磁超晶格的推迟模式

Retarded modes of lateral ferromagnetic/ferromagnetic superlattice

用等效介质理论计算了半无限侧向铁磁/铁磁超晶格的推迟模式.且以Co/Ni体系超晶格为例具体计算了该超晶格的表面模式和体模式,展示出一些与磁性/非磁性超晶格不同的有趣性质.侧向磁性/磁性超晶格具有较复杂的推迟模式,这是一种具有高度一般性的体系,在改变构成超晶格的两种铁磁层的厚度的比值、外场时,可以调节两支表面模式的频率以及体模式的频带,这种调节作用是与两种铁磁层的饱和磁化值有关的.当饱和磁化值相差较大时,调制效果是很明显的.当第二种铁磁介质饱和磁化值趋于零时,该体系演变成熟知的磁性/非磁性超晶格.当取麦克斯韦方程中的介电系数趋于零时,推迟模式将过渡到铁磁/铁磁超晶格的静磁模式.

In this paper, we calculated the retarded modes of semi-infinite lateral ferromagnetic/ ferromagnetic superlattice with the effective-medium theory. We took the Co/Ni system surface modes and bulk modes as the examples for the superlattice and found some interesting properties different from that of the lateral ferromagnetic/nonmagnetic superlattice. Lateral magnetic/magnetic superlattice have some complex retarded modes which are very common in the systems. Changing the ratio of the thicknesses of the ferromagnetic layers, the two branches of surface mode frequency and bulk mode frequency band can be adjusted consequently. This tailoring effect is related to the two ferromagnetic layers＇ saturation magnetization values, and it is quite pronounced when the two saturation magnetization values are quite different from each other. If the difference between the tow values is large, the tailoring effect of fl is more obvious. When the saturation magnetization value of the second ferromangtic medium approaches to zero, this system will become the magnetic/nonmagnetic superlattice. If in Maxwell equation ε = 0, the retarded modes will transit to the ferromangtic/ferromangnetic superlattice magnetostatic modes.