Influence of heat flow control on dynamical spin injection in CoFeB/Pt/CoFeB trilayer

A dynamical spin injection based on the ferromagnetic resonance in a ferromagnetic/nonmagnetic bi-layered structure, is a powerful mean for generating and manipulating the spin current. Although the mechanism of the dynamical spin injection is mainly attributed to the spin pumping, the detailed mechanism and the quantitative understanding for related phenomena are still controversial. As an another important contribution to the dynamical spin injection, the heating effect due to the resonant precessional motion of the magnetization is pointed out recently. In order to quantify the contribution from the heating effect, we here investigate the dynamical spin injection in a CoFeB/Pt/CoFeB trilayer. Although the contribution from the spin pumping diminishes because of the symmetric spin injection from the upper and lower interfaces, a significant inverse spin Hall voltage has been clearly observed. We show that the observed voltage can be quantitatively understood by the thermal spin injection due to a heating effect during the ferromagnetic resonance. A proper combination between the spin pumping and the heat-flow control in the multi-layered system is a key for the efficient dynamical spin injection.