Department of Electrical Engineering, Device Research Laboratory, University of California, Los Angeles, California 90095, USA.
Phys Rev Lett. 2013 Apr 26;110(17):177202. doi: 10.1103/PhysRevLett.110.177202. Epub 2013 Apr 22.
Thermally induced domain wall motion in a magnetic insulator was observed using spatiotemporally resolved polar magneto-optical Kerr effect microscopy. The following results were found: (i) the domain wall moves towards hot regime; (ii) a threshold temperature gradient (5 K/mm), i.e., a minimal temperature gradient required to induce domain wall motion; (iii) a finite domain wall velocity outside of the region with a temperature gradient, slowly decreasing as a function of distance, which is interpreted to result from the penetration of a magnonic current into the constant temperature region; and (iv) a linear dependence of the average domain wall velocity on temperature gradient, beyond a threshold thermal bias. Our observations can be qualitatively explained using a magnonic spin transfer torque mechanism, which suggests the utility of magnonic spin transfer torque for controlling magnetization dynamics.
利用时空分辨的极角磁光克尔显微镜观察到了磁性绝缘体中热诱导的畴壁运动。结果表明：(i) 畴壁朝着高温区移动；(ii) 存在一个阈值温度梯度（5 K/mm），即诱导畴壁运动所需的最小温度梯度；(iii) 在存在温度梯度的区域之外，畴壁速度有限，且随着距离的增加呈指数衰减，这可以解释为磁振子电流穿透到恒温区；(iv) 平均畴壁速度与温度梯度呈线性关系，超过阈值热偏置。我们的观察结果可以用磁振子自旋转移力矩机制来定性解释，这表明磁振子自旋转移力矩在控制磁化动力学方面具有应用潜力。
