【摘要】 采用微磁学模拟方法研究了CoFe矩形纳米点在方波脉冲场作用下的动力学反磁化过程。研究发现,CoFe矩形纳米点S形微磁结构的反磁化特性与脉冲场强有着密切的关系。存在两种不同的动态反磁化过程。场强较弱时,反磁化首先在磁体两末端及磁体中央分别形反磁化核,而后两边缘畴壁移动到磁体中部重合并逐渐由中间开始向上下两边收缩而消失,完成反磁化过程。场强较大时,反磁化过程中边缘畴壁的磁结构发生变化,逐渐由类似180o的畴壁向类似360o的畴壁转变,导致畴壁移动速度的减缓或被钉扎住。反磁化过程转变为360o畴壁的收缩湮灭过程。由于脉冲场强引起畴壁结构的变化导致反磁化时间随场强的变化表现出非单调减小的趋势。更多还原

【Abstract】 The dynamical reversals of rectangular CoFe nanodot with initial S-state subject to square magnetic field pulse have been studied by using the micromagnetic simulations. It was found that the reversals proceeded through different modes as the pulse amplitude is increased. The reversal begins with the motion of the two end domain walls toward the centre and the formation of another reversal nucleus in the inner part of magnet. For the weak magnetic field pulse, the two end domain walls meet at the centre and, subsequently, shrink from central toward lateral,accomplishing the reversal. As the strength of magnetic field pulse becomes stronger, the domain wall structure transits from an 180 o wall-like structure to 360 o wall-like structure. As a result, the velocity of wall motion decreases. Under a sufficient strong pulse, 360 o domain walls are formed and their motion is prohibited. Consequently, the reversal process is realized through the shrinking and disappearing of the 360 o walls. The reversal time- pulse amplitude curve displays a no monotonous decrease due to the variation of domain wall structure with the pulse strength.更多还原