Quantitative characterization of the spin-orbit torque using harmonic Hall voltage measurements
Quantitative characterization of the spin-orbit torque using harmonic Hall voltage measurements
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DOI：
10.1103/physrevb.89.144425
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发表时间：
2014-04-29
影响因子：
3.7
通讯作者：
Ohno, Hideo
中科院分区：
文献类型：
--
作者：
Hayashi, Masamitsu;Kim, Junyeon;Ohno, Hideo
对电流感应扭矩的深入理解是发展超薄磁性异质结中电流和电压控制磁化动力学的关键。为了评估这种力矩或有效场的大小和方向，已经采用了许多方法。在这里，我们检查绝热(低频)谐波霍尔电压测量，它已经被用来研究有效场。我们推导出了计算面外和面内磁化系统有效场的谐和霍尔电压的解析公式。该公式与基于宏观自旋模型的数值计算相吻合。利用所提出的公式对两种不同的平面磁化薄膜--Pt|CoFeB|MgO和CuIr|CoFeB|MgO进行了研究。后一种体系的有效场与以前报道的用自旋扭矩转换相图测量得到的有效场符合得比较好。我们的结果说明了谐波霍尔电压测量在研究磁性异质结中的电流感生扭矩方面具有广泛的适用性。
Solid understanding of current induced torques is a key to the development of current and voltage controlled magnetization dynamics in ultrathin magnetic heterostructures. To evaluate the size and direction of such torques, or effective fields, a number of methods have been employed. Here, we examine the adiabatic (low-frequency) harmonic Hall voltage measurement that has been used to study the effective field. We derive an analytical formula for the harmonic Hall voltages to evaluate the effective field for both out of plane and in-plane magnetized systems. The formula agrees with numerical calculations based on a macrospin model. Two different in-plane magnetized films, Pt|CoFeB|MgO and CuIr|CoFeB|MgO are studied using the formula developed. The effective field obtained for the latter system shows relatively good agreement with that estimated using spin torque switching phase diagram measurements reported previously. Our results illustrate the versatile applicability of harmonic Hall voltage measurement for studying current induced torques in magnetic heterostructures.