磁性纳米线反磁化机制的微磁学模拟

Micromagnetic simulation of magnetization reversal mechanism in magnetic nanowires

通过微磁学模拟手段对长径比均为10的不同直径纳米线的反磁化机制进行了系统研究,发现磁反转模式强烈地依赖于纳米线的直径。直径很小时,反转模式为一致反转;随着直径增大,反转模式过渡为两种不同类型磁化核(一致截面的磁化核或涡旋截面的磁化核)的形成与传播;对于更大直径的纳米线,纳米线中出现多畴结构,反转过程通过多畴涡旋中心的移动来实现,涡旋中心的移动满足右手定则;得到了各种反磁化机制过渡的临界尺寸。计算了不同直径纳米线的矫顽力,并与实验数据进行了比较,从反磁化机制的角度解释了矫顽力随直径的变化关系。

The magnetization reversal mechanism of magnetic nanowires with different diameters but the same aspect ratio 10 were investigated by micromagnetic simulation. The results show that the reversal mechanism significantly depends on the nanowire diameter. For the smallest wire, the reversal model is coherent rotation . With the increase of diameter, magnetization reversal takes place via different nucleation (the transverse domain wall or the vortex domain wall) and subsequent propagation. For the larger nanowire, multidomain will form within the wire, the magnetization reversal is determined by the motion of vortexs which comforms to the right hand rule. The critical diameters of different reversal mechanism are obtained. The coercivities of nanowires with different diameters are calculated and compared with experimental data, the change of coercivity with diameter is interpreted in terms of magnetization reversal mechanism.