Magnon theory for the spin Peltier effect

We propose a model based on the magnonic current to describe the spin Peltier effect in ferromagnetic insulator/paramagnetic heavy metal bilayers. Through the linear Boltzmann's theory, the diffusive regime of magnons into the ferromagnetic layer and the creation/annihilation of magnons at the interface are identified as the main ingredients of the SPE. The dependence of the temperature change at the interface as a function of the charge current, ferromagnetic layer thickness and magnon diffusion length are obtained. The model is applied to the yttrium-iron-garnet/Pt, where a good agreement between theory and recently reported experimental data is achieved.