绝热自旋转移矩驱动的畴壁动力学
Domain wall dynamics driven by adiabatic spin transfer torques
摘要：
在第一近似中，称为绝热过程，电流的自旋极化方向平行于畴壁中的局部磁化矢量。因此，在磁畴壁内的自旋电流的方向的空间变化的结果在磁化上的一个解析的自旋转移力矩。我们表明，由这个自旋力矩驱动的畴壁运动有许多独特的功能，不存在于传统的壁运动由磁场驱动。通过解析和数值求解Landau-Lifshitz-Gilbert方程以及磁性纳米线中的绝热自旋矩，我们发现畴壁在初始施加电流时具有最大速度，但随着畴壁在其运动过程中开始变形，速度减小到零。我们计算了纳米线的畴壁位移和畴壁变形，并得出结论：基于自旋电流在畴壁中绝热传播的自旋力矩不能维持畴壁运动。我们还引入了一个新的概念，畴壁电感来表征的能力的自旋扭矩感生的磁能存储在畴壁。在畴壁钉扎中心存在的情况下，我们构造了磁场和自旋电流共同作用下畴壁脱钉扎的相图。
英文摘要：
In a first approximation, known as the adiabatic process, the direction of the spin polarization of currents is parallel to the local magnetization vector in a domain wall. Thus the spatial variation of the direction of the spin current inside the domain wall results in an adiabatical spin transfer torque on the magnetization. We show that domain wall motion driven by this spin torque has many unique features that do not exist in the conventional wall motion driven by a magnetic field. By analytically and numerically solving the Landau-Lifshitz-Gilbert equation along with the adiabatic spin torque in magnetic nanowires, we find the domain wall has its maximum velocity at the initial application of the current but the velocity decreases to zero as the domain wall begins to deform during its motion. We have computed domain wall displacement and domain wall deformation of nanowires, and concluded that the spin torque based on the adiabatic propagation of the spin current in the domain wall is unable to maintain wall movement. We also introduce a novel concept of domain wall inductance to characterize the capacity of the spin-torque induced magnetic energy stored in a domain wall. In the presence of domain wall pinning centers, we construct a phase diagram for the domain wall depinning by the combined action of the magnetic field and the spin current.
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