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arXiv 0910.2890cond-mat.mes-hallcond-mat.stat-mech
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从铁磁自由度的观点看自旋转移

Spin Transfer from the point of view of the ferromagnetic degrees of freedom

J. -E. Wegrowe

摘要:

自旋电子学是描述耦合到发电机的磁性系统的通用术语,考虑到附着到载流子的自旋。在这篇关于{ \it Spin Caloritronics}的专题综述中,我们集中精力研究自旋电子器件中的{ \it不可逆过程},它涉及到传导电子的自旋和铁磁自由度。本报告的目的是澄清不同种类的功率消耗在金属铁磁体接触到一个发电机的性质,并利用它在介观非平衡态热力学理论的框架。由连接到不同储层的通用系统耗散的内部功率(即内部熵产生乘以温度)的表达式允许通过引入相关唯象动力学系数来导出相应的动力学方程。在推导了铁磁自由度的动力学方程(即Landau-Lifshitz方程)和自旋累积效应的动力学方程(在双通道模型内)之后,得到了描述自旋转移的动力学方程。考虑了自旋相关弛豫(通常的自旋积累)和准弹道区域的自旋进动(横向自旋积累)。然后进行了推广的朗道-Lifshitz方程的自旋积累的两个势能项的引入,这是实验上可以访问。

英文摘要:

Spintronics is the generic term that describes magnetic systems coupled to an electric generator, taking into account the spin attached to the charge carriers. For this topical review of {\it Spin Caloritronics}, we focus our attention on the study of {\it irreversible processes} occuring in spintronic devices, that involve both the spins of the conduction electrons and the ferromagnetic degrees of freedom. The aim of this report is to clarify the nature of the different kinds of power dissipated in metallic ferromagnets contacted to an electric generator, and to exploit it in the framework of the theory of mesoscopic non-equilibrium thermodynamics. The expression of the internal power (i.e. the internal entropy production multiplied by the temperature) dissipated by a generic system connected to different reservoirs, allows the corresponding kinetic equations to be derived with the introduction of the relevant phenomenological kinetic coefficients. After derivation of the kinetic equations for the ferromagnetic degrees of freedom (i.e. the Landau-Lifshitz equation) and the derivation of the kinetic equations for the spin-accumulation effects (within a two channel model), the kinetic equations describing spin-transfer are obtained. Both spin-dependent relaxation (usual spin-accumulation) and spin-precession in quasi-ballistic regime (transverse spin-accumulation) are taken into account. The generalization of the Landau-Lifshitz equation to spin-accumulation is then performed with the introduction of two potential energy terms, that are experimentally accessible.

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