Martinez Eduardo, Torres Luis, Perez Noel, Hernandez Maria Auxiliadora, Raposo Victor, Moretti Simone
Universidad de Salamanca. Plaza de los Caidos s/n, E-37008, Salamanca. Spain.
Sci Rep. 2015 Jun 10;5:10156. doi: 10.1038/srep10156.
Spin orbit interactions are rapidly emerging as the key for enabling efficient current-controlled spintronic devices. Much work has focused on the role of spin-orbit coupling at heavy metal/ferromagnet interfaces in generating current-induced spin-orbit torques. However, the strong influence of the spin-orbit-derived Dzyaloshinskii-Moriya interaction (DMI) on spin textures in these materials is now becoming apparent. Recent reports suggest DMI-stabilized homochiral domain walls (DWs) can be driven with high efficiency by spin torque from the spin Hall effect. However, the influence of the DMI on the current-induced magnetization switching has not been explored nor is yet well-understood, due in part to the difficulty of disentangling spin torques and spin textures in nano-sized confined samples. Here we study the magnetization reversal of perpendicular magnetized ultrathin dots, and show that the switching mechanism is strongly influenced by the DMI, which promotes a universal chiral non-uniform reversal, even for small samples at the nanoscale. We show that ultrafast current-induced and field-induced magnetization switching consists on local magnetization reversal with domain wall nucleation followed by its propagation along the sample. These findings, not seen in conventional materials, provide essential insights for understanding and exploiting chiral magnetism for emerging spintronics applications.
自旋轨道相互作用正迅速成为实现高效电流控制自旋电子器件的关键。许多工作都集中在重金属/铁磁体界面处的自旋轨道耦合在产生电流诱导自旋轨道转矩方面的作用。然而，自旋轨道衍生的Dzyaloshinskii-Moriya相互作用（DMI）对这些材料中自旋纹理的强烈影响现在正变得明显。最近的报告表明，DMI稳定的同手性畴壁（DWs）可以通过自旋霍尔效应产生的自旋转矩高效驱动。然而，DMI对电流诱导的磁化翻转的影响尚未得到探索，也尚未得到很好的理解，部分原因是在纳米尺寸的受限样品中难以区分自旋转矩和自旋纹理。在这里，我们研究了垂直磁化超薄点的磁化翻转，并表明开关机制受到DMI的强烈影响，即使对于纳米尺度的小样品，DMI也会促进一种普遍的手性非均匀翻转。我们表明，超快电流诱导和场诱导的磁化翻转包括局部磁化翻转以及畴壁成核，随后畴壁沿样品传播。这些在传统材料中未观察到的发现，为理解和利用手性磁性以用于新兴的自旋电子学应用提供了重要的见解。
