Generic Seebeck Effect From Spin Entropy

TL;DR

This paper reveals a universal spin entropy contribution to the Seebeck effect in magnetic materials, arising from thermal spin fluctuations of delocalized electrons, which could enable advanced magnetic thermoelectric devices.

Contribution

It introduces a thermodynamic framework showing a generic spin contribution to the Seebeck effect in various magnetic compounds, extending understanding beyond conventional diffusion mechanisms.

Findings

Spin contribution to Seebeck effect exists over a wide temperature range.

Transport spin entropy significantly influences thermoelectric properties.

Potential for developing efficient magnetic thermoelectric devices.

Abstract

How magnetism affects the Seebeck effect is an important issue widely concerned in the thermoelectric community yet remaining elusive. Based on a thermodynamic analysis of spin degrees of freedom on varied $d$-electron based ferro- and anti-ferromagnets, 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 to efficient "magnetic thermoelectrics".