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 (1 h) 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 19 K, 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 = 10 K). The observed enhancement in VISHE has been ascribed to higher surface moment density and good surface quality. •Order of magnitude higher longitudinal spin Seebeck coefficient in Au/polycrystalline Y3Fe5O12 than reported in literature.•The higher spin Seebeck signal due to higher density of surface magnetic moments and improved surface quality.•The observed higher spin Seebeck signal will be useful in flexible spin Seebeck devices and spin-caloritronics area.•The ferrimagnetic order determined using the microscopic neutron diffraction technique in polycrystalline Y3Fe5O12 sample.