铋的磁塞贝克效应
Magneto-Seebeck effect in bismuth
摘要：
大约两个世纪前，人们在铋中发现了热电现象。这种半金属的大而负的Seebeck系数在300 K和100 K之间几乎保持平坦。这个显著的特征可以通过考虑电子和空穴迁移率的比率以及它们的等密度随温度的演变来理解。另一方面，铋中大的各向异性磁塞贝克效应至今尚未被理解。在这里，我们报告了一个系统的研究铋的热电势从室温下到20 K时，应用程序的磁场为13.8 T的二进制biseclampsia平面。Seebeck系数的幅度取决于磁场的方向，并且各向异性随着温度的降低而改变符号。磁塞贝克效应在低温下变得非单调。当磁场沿二元轴取向时，正磁场和负磁场的塞贝克系数不同。这种所谓的乌姆克尔效应的出现是因为费米面椭球的高对称轴既不相互平行，也不平行于晶格的高对称轴。热电势的复杂演化可以在（$T,B,Θ$）空间的很大一部分中通过基于半经典输运理论并结合朗道量子化的模型来解释。所采用的散射时间的能量依赖性是兼容的电声声子散射。我们发现，横向能斯特响应起着重要的作用，在设置纵向磁塞贝克效应的幅度。此外，朗道量子化显着影响热电高达120 K的温度。
英文摘要：
Thermoelectricity was discovered almost two centuries ago in bismuth. The large and negative Seebeck coefficient of this semimetal remains almost flat between 300 K and 100 K. This striking feature can be understood by considering the ratio of electron and hole mobilities and the evolution of their equal densities with temperature. The large and anisotropic magneto-Seebeck effect in bismuth, on the other hand, has not been understood up to the present day. Here, we report on a systematic study of the thermopower of bismuth from room temperature down to 20 K upon application of a magnetic field of 13.8 T in the binary-bisectrix plane. The amplitude of the Seebeck coefficient depends on the orientation of the magnetic field and the anisotropy changes sign with decreasing temperature. The magneto-Seebeck effect becomes non-monotonic at low temperatures. When the magnetic field is oriented along the binary axis, the Seebeck coefficient is not the same for positive and negative fields. This so-called Umkehr effect arises because the high symmetry axes of the Fermi surface ellipsoids are neither parallel to each other nor to the high symmetry axes of the lattice. The complex evolution of thermopower can be accounted for in a large part of the ($T,B,Θ$)-space by a model based on semiclassical transport theory and incorporating Landau quantization. The employed energy dependence of the scattering time is compatible with electron-acoustic phonon scattering. We find that the transverse Nernst response plays an important role in setting the amplitude of the longitudinal magneto-Seebeck effect. Furthermore, Landau quantization significantly affects thermoelectricity up to temperatures as high as 120 K.
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