Enhanced Longitudinal Spin Seebeck Effect in Au/ Y3Fe5O12

We report enhanced longitudinal spin Seebeck coefficient in Au/polycrystalline Y3Fe5O12 (YIG) system in polycrystalline pellets with higher density of surface magnetic moments and a good surface finish. The surface finish, with low artifacts, of the YIG pellet was achieved by using the oxide polishing suspension for a single long-duration of time (1hour) with controlled pressure, in addition to the normal practice of diamond polishing. The longitudinal spin Seebeck effect (LSSE) voltage (VISHE) for the Au/polycrystalline YIG system is found to vary sinusoidally as a function of external magnetic field direction (θ), and increases linearly with the applied temperature difference (ΔT). The observed values of longitudinal spin Seebeck coefficient S are 0.163 and 0.181 μV/K at ΔT = 11 and 19K, respectively. The observed LSSE coefficient in the present study is ~11.1 times of the reported value of 0.016 μV/K for Au/ polycrystalline YIG system (at ΔT = 10K). The observed enhancement in VISHE has been ascribed to higher surface moment density and good surface quality.