Study of magneto-thermal resistance effect in a Co50Fe50/Cu multilayer through the analysis of electron and lattice thermal conductivities

TL;DR

This paper explores the giant magneto-thermal resistance effect in Co50Fe50/Cu multilayers, revealing significant contributions from spin-dependent heat carriers and demonstrating record-high thermal switching at room temperature.

Contribution

It provides a combined experimental and theoretical analysis of the GMTR effect, highlighting the role of spin-dependent heat carriers beyond electron contributions.

Findings

Record-high GMTR of 37 W/m·K at room temperature.

Electron thermal conductivity accounts for only 35% of the GMTR.

Spin-dependent heat carriers significantly influence lattice thermal conductivity.

Abstract

This study investigates the giant magneto-thermal resistance (GMTR) effect in a fully-bcc epitaxial Co50Fe50/Cu multilayer through both experimental and theoretical approaches. The applied magnetic field results in a giant change of the cross-plane thermal conductivity ({\Delta}\k{appa}) of 37 W m-1 K-1, which reaches 1.5 times larger than the previously reported value for a magnetic multilayer and record the highest value at room temperature among the other solid-state thermal switching materials working on different principles. We investigated the electron thermal conductivity for exploring the remarkable {\Delta}\k{appa} by the two-current-series-resistor model combined with the Wiedemann-Franz (WF) law. However, the result shows the electron contribution accounts for only 35% of the {\Delta}\k{appa}, indicating the presence of additional spin-dependent heat carriers. Further investigation of the lattice thermal conductivity, which is expected to be spin-independent, using non-equilibrium molecular dynamics (NEMD) simulations suggests a striking contrast: the additional spin-dependent heat carrier contribution is significantly enhanced in the parallel magnetization configuration but nearly negligible in the antiparallel configuration. These findings provide a fundamental insight into the origin of large GMTR effect and highlight its potential of active thermal management technologies for future electronic devices.