Phase-transition-induced giant Thomson effect for thermoelectric cooling

TL;DR

This paper reports the discovery of a giant Thomson effect in FeRh-based alloys caused by magnetic phase transitions, enabling efficient electronic cooling and opening new avenues for thermoelectric thermal management.

Contribution

The study demonstrates a significantly enhanced Thomson effect in FeRh alloys near room temperature due to magnetic phase transitions, a novel observation in thermoelectric materials.

Findings

Thomson coefficient approaches -1000 μV/K near room temperature.

Thomson cooling exceeds Joule heating in the material.

Effect tunable by magnetic field and composition adjustments.

Abstract

The Seebeck and Peltier effects have been widely studied and used in various thermoelectric technologies, including thermal energy harvesting and solid-state heat pumps. However, basic and applied studies on the Thomson effect, another fundamental thermoelectric effect in conductors, are limited despite the fact that the Thomson effect allows electronic cooling through the application of a temperature gradient bias rather than the construction of junction structures. In this article, we report the observation of a giant Thomson effect that appears owing to magnetic phase transitions. The Thomson coefficient of FeRh-based alloys reaches large values approaching $-$1,000 $\mu$VK$^{-1}$ around room temperature because of the steep temperature dependence of the Seebeck coefficient associated with the antiferromagnetic-ferromagnetic phase transition. The Thomson coefficient is several orders of magnitude larger than the Seebeck coefficient of the alloys. Using the active thermography technique, we demonstrate that the Thomson cooling can be much larger than Joule heating in the same material even in a nearly steady state. The operation temperature of the giant Thomson effect in the FeRh-based alloys can be tuned over a wide range by applying an external magnetic field or by slightly changing the composition. Our findings provide a new direction in the materials science of thermoelectrics and pave the way for thermal management applications using the Thomson effect.