Thermally driven spin torques in layered magnetic insulators
Thermally driven spin torques in layered magnetic insulators
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DOI：
10.1103/physrevb.93.064418
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发表时间：
2016-02-17
影响因子：
3.7
通讯作者：
Tserkovnyak, Yaroslav
中科院分区：
文献类型：
--
作者：
Bender, Scott A.;Tserkovnyak, Yaroslav
最近在电绝缘铁磁体|普通金属异质结构中报道了热驱动的自旋转移矩。在本文中，我们针对此类扭矩提出了两种物理上不同的机制。第一个是局部效应：铁磁体中不平衡的热激活磁振子在自旋塞贝克效应的驱动下，通过具有相干动力学的磁振子-磁振子散射对磁化施加扭矩。第二个是非局部效应，需要额外的磁性层来提供实现热扭矩所需的对称性破缺。引起非局部热扭矩的最简单结构是由两个由普通金属垫片隔开的绝缘磁体组成的自旋阀；在那里，热通量通过自旋阀产生纯自旋电流，当层的磁化不对准时，这会产生扭矩。
Thermally driven spin-transfer torques have recently been reported in electrically insulating ferromagnet|normal-metal heterostructures. In this paper, we propose two physically distinct mechanisms for such torques. The first is a local effect: out-of-equilibrium, thermally activated magnons in the ferromagnet, driven by a spin Seebeck effect, exert a torque on the magnetization via magnon-magnon scattering with coherent dynamics. The second is a nonlocal effect which requires an additional magnetic layer to provide the symmetry breaking necessary to realize a thermal torque. The simplest structure in which to induce a nonlocal thermal torque is a spin valve composed of two insulating magnets separated by a normal metal spacer; there, a thermal flux generates a pure spin current through the spin valve, which results in a torque when the magnetizations of the layers are misaligned.