Spin Seebeck effect (SSE) and related spin caloritronics have attracted great interest recently. However, the definition of the SSE coefficient remains to be established, let alone a clean experiment to measure the SSE coefficient in ferromagnetic metals. The concept through a model based on the semi‐classical Botlzmann transport equation has been clarified. The model includes the vital spin‐flip process, which is frequent in metals, and points out that the length scale of SSE is much larger than the spin diffusion length. The model reveals how the spin‐flip process influences the transport equations and provides the simple relationship between the different spin‐flip relaxation times for spin‐up and ‐down electrons, which is very useful to understand the spin transport properties. This understanding allows to redefine the expression of the spin Seebeck coefficient.

中文翻译：

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铁磁金属中自旋塞贝克效应的概念

自旋塞贝克效应（SSE）和相关自旋量热电子学最近引起了人们的极大兴趣。但是，SSE系数的定义仍有待确定，更不用说进行干净的实验来测量铁磁金属中的SSE系数了。通过基于半经典Botlzmann输运方程的模型的概念已得到阐明。该模型包括重要的自旋翻转过程，这种过程在金属中很常见，并指出SSE的长度尺度远大于自旋扩散长度。该模型揭示了自旋翻转过程如何影响输运方程，并提供了自旋上下电子的不同自旋翻转弛豫时间之间的简单关系，这对于理解自旋输运性质非常有用。