Current-driven dynamics of chiral ferromagnetic domain walls
Current-driven dynamics of chiral ferromagnetic domain walls
复制标题
DOI：
10.1038/nmat3675
复制
发表时间：
2013-07-01
期刊：
影响因子：
41.2
通讯作者：
Beach, Geoffrey S. D.
中科院分区：
文献类型：
--
作者：
Emori, Satoru;Bauer, Uwe;Beach, Geoffrey S. D.
在大多数铁磁体中，磁化强度从一个磁区旋转到下一个磁区，没有偏爱的惯用手。然而，反转对称性的破缺可以提升手性简并，通过Dzyaloshinskii-Moriya相互作用(6)(DMI)导致丰富的自旋织构，如自旋螺旋(1，2)和Skyrmions(3-5)。在这里，我们展示了在夹在重金属和氧化物之间的超薄金属铁磁体中，DMI稳定了手性磁场壁(2，7)(DWS)，其自旋织构使得非常有效的电流驱动运动(8-11)成为可能。结果表明，自旋霍尔效应(12-15)所产生的自旋力矩驱使Pt/CoFe/MgO和Ta/CoFe/MgO中的DWS朝着相反的方向运动，这只有在DWS具有左手手性的Neel组态(7，16)时才能得到解释。我们通过研究垂直和平行于自旋螺旋的磁场作用下的电流驱动的DW动力学，直接证实了DW的手性和刚性。这项工作解决了有争议的实验结果(10，17，18)的起源，并突出了一条通往自旋电子器件界面设计的新途径。
In most ferromagnets the magnetization rotates from one domain to the next with no preferred handedness. However, broken inversion symmetry can lift the chiral degeneracy, leading to topologically rich spin textures such as spin spirals(1,2) and skyrmions(3-5) through the Dzyaloshinskii-Moriya interaction(6) (DMI). Here we show that in ultrathin metallic ferromagnets sandwiched between a heavy metal and an oxide, the DMI stabilizes chiral domain walls(2,7) (DWs) whose spin texture enables extremely efficient current-driven motion(8-11). We show that spin torque from the spin Hall effect(12-15) drives DWs in opposite directions in Pt/CoFe/MgO and Ta/CoFe/MgO, which can be explained only if the DWs assume a Neel configuration(7,16) with left-handed chirality. We directly confirm the DW chirality and rigidity by examining current-driven DW dynamics with magnetic fields applied perpendicular and parallel to the spin spiral. This work resolves the origin of controversial experimental results(10,17,18) and highlights a new path towards interfacial design of spintronic devices.