Investigation of spin Seebeck effect and magnetic damping in nanometer thick Ce0.5Y2.5Fe5O12 films

The ferromagnetic insulators (FMI) involving the phonon-magnon interaction in generation of spin currents are providing new opportunities to explore the thermal to electrical conversion efficiency in comparison to electron based themoelectrics. Here, we have investigated the magnetic damping behavior and spin Seebeck effect in crystalline, highly smooth surfaced, nano-meter thick FMI Ce0.5Y2.5Fe5O12 (CeYIG) films, synthesized via pulsed laser deposition technique, for their application in spin caloritronics. The CeYIG films reveal an increase of saturation magnetization, strong magnetic anisotropy and a very low magnetic damping, optimum for investigation of pure spin currents generated via inverse spin Hall Effect. The room temperature longitudinal spin Seebeck effect (LSSE) was observed on sputtering of 8 nm thick Hall bar patterned rhodium (Rh) on CeYIG films. The magnitude of LSSE voltage obtained showed a characteristic increase and saturation of signal with the increase of film thickness, indicating the origin of spin current generation from the bulk of CeYIG film. The pure spin Hall magnetoresistance (SMR) was observed in temperature range of 5-300 K implying the LSSE observed in Rh layer is purely from the spin current generated within the FMI and free from parasitic magnetic proximity effect (MPE). The use of Rh as a normal metal for the detection of spin current can open a new window in the exploration of pure spin current related phenomena.