标题： 自旋动力学中兰道-利夫希茨-吉尔伯特方程的相对论自旋弛豫机制理论 显示英文标题

标题： Relativistic theory of spin relaxation mechanisms in the Landau-Lifshitz-Gilbert equation of spin dynamics

摘要： 从狄拉克-科恩-沙姆方程出发，我们推导了在外部电磁场作用下磁性固体中自旋角动量的相对论运动方程。 该运动方程可以写成对于谐波外部磁场的著名朗道-利夫希茨-吉尔伯特方程的形式，并且对于一般时变磁场导致更一般的磁化动力学方程。 在这两种情况下，都包含一个电子自旋弛豫项，该项源于自旋-轨道相互作用。 因此，我们从基本原理出发，严格推导出各向异性阻尼张量的一般表达式，该表达式显示包含各向同性的吉尔伯特贡献以及各向异性的伊辛类似和手性、 戴若-莫里亚类似贡献。 自旋弛豫张量的表达式还包括电子的带间和带内跃迁。 我们还表明，当外加电磁场具有自旋角动量时，这将导致对自旋矩施加的光学自旋扭矩。 显示英文摘要

摘要： Starting from the Dirac-Kohn-Sham equation we derive the relativistic equation of motion of spin angular momentum in a magnetic solid under an external electromagnetic field. This equation of motion can be written in the form of the well-known Landau-Lifshitz-Gilbert equation for a harmonic external magnetic field, and leads to a more general magnetization dynamics equation for a general time-dependent magnetic field. In both cases with an electronic spin-relaxation term which stems from the spin-orbit interaction. We thus rigorously derive, from fundamental principles, a general expression for the anisotropic damping tensor which is shown to contain an isotropic Gilbert contribution as well as an anisotropic Ising-like and a chiral, Dzyaloshinskii-Moriya-like contribution. The expression for the spin relaxation tensor comprises furthermore both electronic interband and intraband transitions. We also show that when the externally applied electromagnetic field possesses spin angular momentum, this will lead to an optical spin torque exerted on the spin moment.