坡莫合金纳米环微磁学特性研究

Micromagnetic Properties of Permalloy Nanorings

摘要: 基于微磁学软件MuMax3，我们研究了外磁场下不同几何形状的磁性纳米环(Ni₈₀Fe₂₀)的磁化翻转过程，除了预期的洋葱态和漩涡磁化状态外，在磁化过程中还观察到其它亚稳态。通过磁矩翻转相图和能量密度关系，分析了不同磁化状态的形成和跃迁，以及磁矩翻转过程中畴壁的传播和湮灭。我们进一步研究了极化电流驱动Ni₈₀Fe₂₀/Cu/Ni₈₀Fe₂₀磁性隧道结中磁矩翻转的过程，研究发现，纳米环隧道结磁矩翻转的电流密度为3.4 × 10⁷ A/cm²，临界电流密度大小为传统隧道结的0.63倍，两者的磁矩翻转时间大致相同，约为1000 ps。

Abstract: Based on the micromagnetic software MuMax3, we studied the magnetization reversal process of different geometric shapes of magnetic nanorings (Ni₈₀Fe₂₀) in an external magnetic field. In addition to the expected onion state and vortex magnetization state, other metastable states were observed in the magnetization process. The formation and transition of different magnetization states, as well as the propagation and annihilation of domain walls in the process of magnetic moment reversal are analyzed through the phase diagram and energy density relationship. Furthermore, we studied the process of magnetic moment reversal in Ni₈₀Fe₂₀/Cu/Ni₈₀Fe₂₀ magnetic tunnel junctions driven by polarization current. The results show that the current density of magnetic moment reversal in nanoring tunnel junctions is 3.4 × 10⁷ A/cm², and the critical current density is 0.63 times of that in traditional tunnel junctions. The time of magnetic moment reversal is about 1000 ps.