Effective thermal boundary resistance from thermal decoupling of magnons and phonons in SrRuO3 thin films

We use the time-resolved magneto-optical Kerr effect 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. © 2010 The American Physical Society.