Bias-voltage dependence of perpendicular spin-transfer torque in asymmetric MgO-based magnetic tunnel junctions

Se Chung Oh, Seung Young Park, Aurelien Manchon, Mairbek Chshiev, Jae Ho Han, Hyun Woo Lee, Jang Eun Lee, Kyung Tae Nam, Younghun Jo, Yo Chan Kong, Bernard Dieny, Kyung-Jin Lee

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Spin-transfer torque (STT) allows the electrical control of magnetic states in nanostructures. The STT in magnetic tunnel junctions (MTJs) is of particular importance owing to its potential for device applications. It has been demonstrated that the MTJ has a sizable perpendicular STT (, field-like torque), which substantially affects STT-driven magnetization dynamics. In contrast to symmetric MTJs where the bias dependence of is quadratic, it is theoretically predicted that the symmetry breaking of the system causes an extra linear bias dependence. Here, we report experimental results that are consistent with the predicted linear bias dependence in asymmetric MTJs. The linear contribution is quite significant and its sign changes from positive to negative as the asymmetry is modified. This result opens a way to design the bias dependence of the field-like term, which is useful for device applications by allowing, in particular, the suppression of the abnormal switching-back phenomena. © 2009 Macmillan Publishers Limited. All rights reserved.
Original languageEnglish (US)
Pages (from-to)898-902
Number of pages5
JournalNature Physics
Issue number12
StatePublished - Oct 25 2009

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