Large spin Hall magnetoresistance and its correlation to the spin-orbit torque in W/CoFeB/MgO structures.
Large spin Hall magnetoresistance and its correlation to the spin-orbit torque in W/CoFeB/MgO structures.
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DOI：
10.1038/srep14668
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发表时间：
2015-10-01
影响因子：
4.6
通讯作者：
Park BG
中科院分区：
文献类型：
--
作者：
Cho S;Baek SC;Lee KD;Jo Y;Park BG
重金属/铁磁/氧化物结构中基于自旋-轨道相互作用的现象因其适用于通过面内电流控制磁化方向而被广泛研究。这意味着存在相反的效应，在这种效应中，这种结构中的导电性应该取决于磁化方向。在本工作中，我们系统地研究了W/CoFeB/MgO结构的磁阻(MR)及其与电流感应扭矩对磁化强度的关系。我们观察到，磁流变与磁化强度和电流方向之间的夹角无关，而是由自旋霍尔效应积累的自旋方向相对于自旋方向的相对磁化取向决定的，其对称性与所谓的自旋霍尔磁阻相同。W/CoFeB/MgO样品中~1%的磁阻比Ta/CoFeb/MgO或Pt/Co/AlOx中的磁阻要大得多，这表明W的自旋霍尔角较大。此外，磁阻与电流感生磁化转换效率的相似W厚度关系表明，非磁/铁磁结构中的磁阻可以用来理解其他密切相关的自旋-轨道耦合效应，如反自旋霍尔效应或自旋-轨道自旋转移扭矩。
The phenomena based on spin-orbit interaction in heavy metal/ferromagnet/oxide structures have been investigated extensively due to their applicability to the manipulation of the magnetization direction via the in-plane current. This implies the existence of an inverse effect, in which the conductivity in such structures should depend on the magnetization orientation. In this work, we report a systematic study of the magnetoresistance (MR) of W/CoFeB/MgO structures and its correlation with the current-induced torque to the magnetization. We observe that the MR is independent of the angle between the magnetization and current direction but is determined by the relative magnetization orientation with respect to the spin direction accumulated by the spin Hall effect, for which the symmetry is identical to that of so-called the spin Hall magnetoresistance. The MR of ~1% in W/CoFeB/MgO samples is considerably larger than those in other structures of Ta/CoFeB/MgO or Pt/Co/AlOx, which indicates a larger spin Hall angle of W. Moreover, the similar W thickness dependence of the MR and the current-induced magnetization switching efficiency demonstrates that MR in a non-magnet/ferromagnet structure can be utilized to understand other closely correlated spin-orbit coupling effects such as the inverse spin Hall effect or the spin-orbit spin transfer torques.