矩形磁性纳米点动力学反磁化过程的微磁学研究

采用微磁学模拟方法研究了初始态为C形磁结构的矩形CoFe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，随着脉冲场强的增强，磁体的反磁化模式发生了改变.当场强较弱时反磁化过程通过畴壁移动-单涡旋的形成和移动来完成；当场强较大时反磁化过程模式转变为畴壁移动-双涡旋的形成与移动；在更强的场强下反磁化过程通过畴壁的移动-多涡旋的形成与湮没来实现.由于反磁化模式随场强的变化而改变，反磁化时间随场强的增大出现振荡变化现象. 关键词： 动力学反磁化过程 反磁化时间 微磁学模拟

Dynamical reversal of rectangular nanodot studied by micromagnetics

The dynamical reversal of rectangular CoFe nanodot with initial C-state subject to square magnetic field pulse has been studied by using the micromagnetic simulations. It was found that the reversals proceeded through different modes as the pulse amplitude is increased. For the weak magnetic field pulse， the magnetization reversal is realized through the motion of the end domain walls toward the central part of magnet and， subsequently， the formation and motion of a single vortex. As the strength of magnetic field pulse become stronger， the reversal is accomplished through the motion of the end domain walls plus the formation and motion of two vortex structure. For much stronger field pulse the reversal process is the motion of the end domain walls and subsequent formation and annihilation of several vortices. The dependence of reversal time on the field pulse amplitude displays oscillating characteristic due to the transitions of reversal modes with the field strength.