Evolution of the Spin Hall Magnetoresistance in Cr$_2$O$_3$/Pt bilayers close to the N\'eel temperature
Evolution of the Spin Hall Magnetoresistance in Cr$_2$O$_3$/Pt bilayers close to the N\'eel temperature
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DOI：
10.1063/1.5019934
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发表时间：
2017-12
期刊：
影响因子：
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通讯作者：
R. Schlitz;T. Kosub;Andy Thomas;Savio Fabretti;K. Nielsch;D. Makarov;S. Goennenwein
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文献类型：
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作者：
R. Schlitz;T. Kosub;Andy Thomas;Savio Fabretti;K. Nielsch;D. Makarov;S. Goennenwein
我们研究了由铂和易轴在平面外的反铁磁体 Cr$_2$O$_3$ 组成的薄膜双层中磁阻随温度的变化。我们将温度从 20 - 60{\deg}C 变化，接近 Cr$_2$O$_3$ 的 N\'eel 温度，约为 37{\deg}C。在外部磁场在三个相互正交的平面中旋转期间记录磁阻响应。在 Cr$_2$O$_3$ 的顺磁相中观察到具有与正自旋霍尔磁阻一致的对称性的大磁阻，然而当冷却到低于 N\'eel 温度时，该磁阻消失。与 Gd$_3$Ga$_5$O$_{12}$/Pt 异质结构中的类似实验相比，我们得出结论，绝缘体中的顺磁场感应磁化不足以解释观察到的磁阻。我们推测界面处磁矩的类型会定性地影响自旋角动量传递，与 Gd 的更局域化的 $4f$ 矩相比，Cr 的 $3d$ 矩下沉角动量的效率要高得多。
We study the evolution of magnetoresistance with temperature in thin film bilayers consisting of platinum and the antiferromagnet Cr$_2$O$_3$ with its easy axis out of the plane. We vary the temperature from 20 - 60{\deg}C, close to the N\'eel temperature of Cr$_2$O$_3$ of approximately 37{\deg}C. The magnetoresistive response is recorded during rotations of the external magnetic field in three mutually orthogonal planes. A large magnetoresistance having a symmetry consistent with a positive spin Hall magnetoresistance is observed in the paramagnetic phase of the Cr$_2$O$_3$, which however vanishes when cooling to below the N\'eel temperature. Comparing to analogous experiments in a Gd$_3$Ga$_5$O$_{12}$/Pt heterostructure, we conclude that a paramagnetic field induced magnetization in the insulator is not sufficient to explain the observed magnetoresistance. We speculate that the type of magnetic moments at the interface qualitatively impacts the spin angular momentum transfer, with the $3d$ moments of Cr sinking angular momentum much more efficiently as compared to the more localized $4f$ moments of Gd.