Laser-heating spin Seebeck effect of yttrium iron garnet/platinum heterostructure below room temperature

Longitudinal spin Seebeck effect (LSSE) refers to generate spin accumulation in ferromagnetic material by thermal gradient, and the spin accumulation can transfer to the attached heavy metal and convert to charge current through inverse spin Hall effect (ISHE). However, the origin of LSSE has been under debate for a long time. In this paper, we prepared the YIG/Pt heterostructure by pulsed laser deposition and magnetron sputter, and studied the relationship between temperature and the voltage of inverse spin Hall effect (V_ISHE). It is found that the V_ISHE vs T curve measured under zero-field (ZFC) and nonzero-field (FC) condition are not coincident with each other, meaning there might exist some spin glass states in the system which may come from the YIG/Pt interface. Moreover, we also compare the experimental data and magnon spin current theory prediction which considers both the bulk magnon spin current effect and the interfacial spin pumping process in the interface. It is found that there is a big deviation between them, meaning that the interface effect may play a crucial role in the temperature-dependent LSSE, especially in low temperature. This work will provide deep insight into the spin transport behavior of the YIG/Pt heterostructure.