Skinner Brian, Fu Liang
Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
Sci Adv. 2018 May 25;4(5):eaat2621. doi: 10.1126/sciadv.aat2621. eCollection 2018 May.
The thermoelectric effect is the generation of an electrical voltage from a temperature gradient in a solid material due to the diffusion of free charge carriers from hot to cold. Identifying materials with a large thermoelectric response is crucial for the development of novel electric generators and coolers. We theoretically consider the thermopower of Dirac/Weyl semimetals subjected to a quantizing magnetic field. We contrast their thermoelectric properties with those of traditional heavily doped semiconductors and show that, under a sufficiently large magnetic field, the thermopower of Dirac/Weyl semimetals grows linearly with the field without saturation and can reach extremely high values. Our results suggest an immediate pathway for achieving record-high thermopower and thermoelectric figure of merit, and they compare well with a recent experiment on Pb Sn Se.
热电效应是指由于固体材料中自由电荷载流子从热端向冷端扩散，在温度梯度作用下产生电势差。识别具有大热电响应的材料对于新型发电机和冷却器的开发至关重要。我们从理论上考虑了处于量子化磁场中的狄拉克/外尔半金属的热功率。我们将它们的热电特性与传统重掺杂半导体的热电特性进行对比，结果表明，在足够强的磁场下，狄拉克/外尔半金属的热功率随磁场线性增长且不饱和，并能达到极高的值。我们的结果为实现创纪录的高热功率和热电优值提供了一条直接途径，并且与最近关于PbSnSe的实验结果吻合得很好。
