Evidence for effective thermal boundary resistance from magnon/phonon disequilibrium

TL;DR

This study demonstrates that magnon/phonon disequilibrium causes an effective thermal boundary resistance at the interface of ferromagnetic SrRuO3 thin films, affecting heat flow dynamics as measured by TRMOKE.

Contribution

It provides experimental evidence linking magnon/phonon disequilibrium to thermal boundary resistance in ferromagnetic thin films.

Findings

Heat flow out of the film is limited by the film/substrate interface.

Exponential decay of film temperature indicates boundary resistance.

Magnon/phonon disequilibrium contributes to thermal boundary effects.

Abstract

We use the time-resolved magneto-optical Kerr effect (TRMOKE) to measure the local temperature and heat flow dynamics in ferromagnetic SrRuO3 thin films. After heating by a pump pulse, the film temperature decays exponentially, indicating that the heat flow out of the film is limited by the film/substrate interface. We show that this behavior is consistent with an effective boundary resistance resulting from disequilibrium between the spin and phonon temperatures in the film.