磁化强度调制的圆柱形纳米线磁子晶体

Magnonic crystal based on magnetization-modulated cylindrical nanowire

采用微磁学模拟的方法研究了自旋波在磁化强度周期变化的圆柱形纳米线中的传播特性。结果显示,频谱和色散关系图中均能看到明显的自旋波通带和禁带。带隙是由自旋波在布里渊区边界处的布拉格反射引起的。通过改变磁子晶体的周期长度、磁化强度比值可以有效的调制自旋波带隙结构。当周期长度增大时,带隙数目增加,带隙频率位置降低,带隙宽度变窄。随着磁化强度调制的增强,带隙位置逐渐降低,而带隙宽度表现出复杂的变化形式,有些带隙表现出振荡行为。这些结果对研制纳米线磁子晶体器件具有参考意义。

The characteristics of spin waves propagating in magnetization-modulated cylindrical nanowire are studied by micromagnetic simulations.The allowed and forbidden spin-wave bands are observed in the frequency spectra and dispersion curves.They are caused by the Bragg reflection of the spin wave modes at the Brillouin zone boundaries.The bandgaps can be effectively controlled by manipulating the period of magnonic crystal or the magnetization ratio.The results show that the number of bandgaps increases with the increase of the period, the bandgaps shift to lower frequency and the bandgap widths decrease.The enhancement of the magnetization modulation also displaces bandgap position toward the low frequency.While the variation of the bandgap widths displays complicated form and some bandgaps exhibit oscillation characteristic.The results presented here may find their use in designing magnonic devices.