Recording Heads Operation, Seagate Technology, 7801 Computer Ave, Bloomington, Minnesota 55435, USA.
Phys Rev Lett. 2010 Aug 6;105(6):066602. doi: 10.1103/PhysRevLett.105.066602.
A steady-state electrical current flowing in a magnetic heterostructure can exert a torque on the magnetization, and provides a means to control magnetization states and dynamics in spintronics structures. However, some components of the torque are difficult to measure and to calculate. We have determined the perpendicular spin torque in MgO magnetic tunnel junctions by measuring their lowest ferromagnetic resonance frequency and find that it decreases linearly with increasing bias voltage. Micromagnetic modeling shows that this decrease is caused by the perpendicular component of spin torque. We obtain a quantitative value for the perpendicular spin torque effective field as a function of bias voltage, and show that this effective field is a linear function in bias voltage and approximately equal in magnitude to the in-plane spin torque effective field.
在磁异质结构中流动的稳定电流会对磁化产生转矩，并为控制自旋电子结构中的磁化状态和动力学提供一种手段。然而，转矩的某些分量难以测量和计算。我们通过测量 MgO 磁隧道结的最低铁磁共振频率来确定其垂直自旋扭矩，发现它随偏置电压的增加呈线性减小。微磁学模型表明，这种减小是由自旋扭矩的垂直分量引起的。我们得到了偏置电压作为函数的垂直自旋扭矩有效场的定量值，并表明该有效场在偏置电压中是线性函数，并且大小近似等于平面内自旋扭矩有效场。
