Magnetization-direction-dependent inverse spin Hall effect observed in IrMn/NiFe/Cu/YIG multilayer structure

The magnetization-direction-dependent inverse spin Hall effect (ISHE) has been observed in NiFe film during spin Seebeck measurement in IrMn/NiFe/Cu/yttrium iron garnet (YIG) multilayer structure, where the YIG and NiFe layers act as the spin injector and spin current detector, respectively. By using the NiFe/IrMn exchange bias structure, the magnetization direction of YIG (M_YIG) can be rotated with respect to that of NiFe (M_NiFe) with a small magnetic field, thus allowing us to observe the magnetization-direction-dependent inverse spin Hall effect voltage in NiFe layer. Compared with the situation that polarization direction of spin current (σ_s) is perpendicular to M_NiFe, the spin Seebeck voltage is about 30% larger than that when σ_s and M_NiFe are parallel to each other. This phenomenon may originate from either or both of stronger interface or bulk scattering to spin current when σ_s and M_NiFe are perpendicular to each other. Our work provides a way to control the voltage induced by ISHE in ferromagnets.