Generic Seebeck effect from spin entropy

Peijie Sun; K Ramesh Kumar; Meng Lyu; Zhen Wang; Junsen Xiang; Wenqing Zhang

doi:10.1016/j.xinn.2021.100101

Generic Seebeck effect from spin entropy

Innovation (Camb). 2021 Mar 26;2(2):100101. doi: 10.1016/j.xinn.2021.100101. eCollection 2021 May 28.

Authors

Peijie Sun^{1

2

3}, K Ramesh Kumar¹, Meng Lyu^{1

2}, Zhen Wang^{1

2}, Junsen Xiang¹, Wenqing Zhang⁴

Affiliations

¹ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
² University of Chinese Academy of Sciences, Beijing 100049, China.
³ Songshan Lake Materials Laboratory, Dongguan 523808, China.
⁴ Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China.

Abstract

How magnetism affects the Seebeck effect is an important issue of wide concern in the thermoelectric community but remains elusive. Based on a thermodynamic analysis of spin degrees of freedom on varied d-electron-based ferromagnets and antiferromagnets, we demonstrate that in itinerant or partially itinerant magnetic compounds there exists a generic spin contribution to the Seebeck effect over an extended temperature range from slightly below to well above the magnetic transition temperature. This contribution is interpreted as resulting from transport spin entropy of (partially) delocalized conducting d electrons with strong thermal spin fluctuations, even semiquantitatively in a single-band case, in addition to the conventional diffusion part arising from their kinetic degrees of freedom. As a highly generic effect, the spin-dependent Seebeck effect might pave a feasible way toward efficient "magnetic thermoelectrics."

Keywords: Seebeck effect; magnetocaloric effect; spin entropy; thermoelectric material.