Magnetothermal resistance effect in a Co50Fe50/Cu multilayer studied via analysis of electron and lattice thermal conductivities

This study investigates the giant magnetothermal 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 (κ) of 37 W m−1 K−1, which reaches 1.5 times larger than the previously reported value for a magnetic multilayer and records 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 κ by the two-current-series-resistor model combined with the Wiedemann-Franz law. However, the result shows the electron contribution accounts for only 35% of the κ, indicating the presence of additional spin-dependent heat carriers. Further investigation of the lattice thermal conductivity, which is expected to be spin independent, using nonequilibrium molecular dynamics 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.