Department of Physics, Texas A&M University, College Station, Texas 77843-4242, USA.
Nat Commun. 2013;4:1945. doi: 10.1038/ncomms2945.
Recently discovered spin-dependent thermoelectric effects have merged spin, charge, and thermal physics, known as spin caloritronics, of which the spin Seebeck effect is its most puzzling. Here we present a theory of this effect driven by subthermal non-local phonon heat transfer and spectral non-uniform temperature. The theory explains its non-local behaviour from the fact that phonons that store the energy (thermal) and the phonons that transfer it (subthermal) are located in different parts of the spectrum and have different kinetics. This gives rise to a spectral phonon distribution that deviates from local equilibrium along the substrate and is sensitive to boundary conditions. The theory also predicts a non-magnon origin of the effect in ferromagnetic metals in agreement with observations in recent experiments. Equilibration of the heat flow from the substrate to the Pt probe and backwards leads to a vertical spin current produced by the spin-polarized electrons dragged by the thermal phonons.
最近发现的自旋相关热电效应将自旋、电荷和热物理融合在一起，称为自旋热电子学，其中自旋塞贝克效应是最令人困惑的。在这里，我们提出了一种由亚热非局域声子热传递和谱非均匀温度驱动的这种效应的理论。该理论从以下事实解释了其非局域行为：存储能量的声子（热）和声子传递能量（亚热）位于光谱的不同部分，具有不同的动力学。这导致声子分布沿衬底偏离局部平衡，并对边界条件敏感。该理论还预测在铁磁金属中，该效应的非磁子起源与最近实验中的观察结果一致。从衬底到 Pt 探针的热流的平衡以及反向平衡导致由热声子拖动的自旋极化电子产生垂直自旋流。
