自旋极化电流辅助的超快反磁化特性研究

Spin-polarized Current-assisted Ultrafast Magnetization Reversal

基于微磁学模拟方法研究了椭圆纳米薄膜的超快反磁化特性。提出一种利用弱直流自旋极化电流辅助的场驱动进动反磁化新机制。新机制可以有效扩宽脉冲持续时间窗口,在宽的脉冲持续时间范围内可实现进动磁反转而无需精确控制;也可有效抑制磁反转后长时间磁振荡,缩短有效反磁化时间。时间窗口的扩宽和进动磁反转后磁振荡的衰减依赖于自旋极化电流密度。磁反转后的磁振荡由多种不同的自旋波模式构成,自旋转移力矩可以调制磁体有效阻尼,加速磁能量的耗散。

The ultrafast magnetization reversal in a thin elliptic magnetic element was studied by micromagnetic simulations. A strategy was presented using a small I3（2 spin-polarized current to assist the precessional magnetization reversal. It was found that the spin-polarized current not only broadened the time window of the pulse duration, in which a successful precessional reversal was achievable, but also significantly suppressed the magnetization ringing af- ter the reversal. The pulse time window as well as the decay rate of the ringing was dependent on the current density. Frequency spectrum analysis showed that the ringing was composed of several spin-wave modes. The spin-transfer torque could shorten the relaxation time of the ringing and reinforce the magnetic damping.