Huge anisotropic magneto-thermal switching in high-purity polycrystalline compensated metals

TL;DR

This paper demonstrates a significant magneto-thermal switching effect in high-purity polycrystalline Pb wires at low temperatures, showing potential for thermal management in space and other low-temperature environments.

Contribution

It reveals that large magneto-thermal switching can occur in polycrystalline metals, expanding potential applications beyond single crystals.

Findings

Thermal conductivity drops from 2500 to 5 W/m·K with increasing magnetic field.

Huge magneto-thermal switching observed at 3 K in polycrystalline Pb.

Potential for practical low-temperature thermal management applications.

Abstract

Magneto-thermal transport is a promising physical property for thermal management applications. Magneto-thermal switching enables active control of heat flows, and a high switching ratio is desirable for improving performance. Here, we report on the observation of a huge magneto-thermal switching (MTS) effect in high-purity (5N) Pb polycrystalline wires, where magnetic fields perpendicular to the heat current direction are applied at low temperatures. At T = 3 K and B = 0.1 T, the measured thermal conductivity (\k{appa}) of the Pb wire is about 2500 W m-1 K-1 but is reduced to ~150 and ~5 W m-1 K-1 at B = 1 and 9 T, respectively. This strong suppression is attributed to magnetoresistance in compensated metals. Although the huge magnetoresistance has been studied in single crystals with field along the selected orbitals, our results demonstrate that a huge MTS can similarly be realized even in flexible polycrystalline wires. This finding highlights the practical potential of magneto-thermal control in low-temperature thermal management, including applications in space environments where temperatures are around 3 K.