Laboratoire de Physique des Solides, Université Paris-Sud, CNRS, 91405 Orsay, France.
J Phys Condens Matter. 2011 Nov 9;23(44):446004. doi: 10.1088/0953-8984/23/44/446004. Epub 2011 Oct 18.
Domain wall dynamics produced by spin transfer torques is investigated in (Ga, Mn)As ferromagnetic semiconducting tracks with perpendicular anisotropy, close to the Curie temperature. The domain wall velocities are found to follow a linear flow regime which only slightly varies with temperature. Using the Döring inequality, boundaries of the spin polarization of the current are deduced. A comparison with the predictions of the mean field k·p theory leads to an estimation of the carrier density whose value is compatible with results published in the literature. The spin polarization of the current and the magnetization of the magnetic atoms present similar temperature variations. This leads to a weak temperature dependence of the spin drift velocity and thus of the domain wall velocity. A combined study of field- and current-driven motion and deformation of magnetic domains reveals a motion of domain walls in the steady state regime without transition to the precessional regime. The ratio between the non-adiabatic torque β and the Gilbert damping factor α is shown to remain close to unity.
（Ga，Mn）As 铁磁半导体轨道中具有垂直各向异性，接近居里温度，研究了由自旋转移力矩产生的畴壁动力学。发现畴壁速度遵循线性流动状态，仅随温度略有变化。利用多林不等式，推导出电流自旋极化的边界。与平均场 k·p 理论的预测进行比较，得到了载流子密度的估计值，其值与文献中公布的结果相兼容。电流的自旋极化和磁原子的磁化具有相似的温度变化。这导致自旋漂移速度和畴壁速度的温度依赖性较弱。磁场和电流驱动运动以及磁畴变形的综合研究表明，在没有过渡到进动状态的情况下，在稳态下畴壁的运动。非绝热扭矩β与吉尔伯特阻尼因子α的比值被证明接近 1。
