Generation of pure spin currents via spin Seebeck effect in self-biased hexagonal ferrite thin films

Light-induced generation of pure spin currents in a Pt(2.5 nm)/BaFe12O19(1.2 μm)/sapphire(0.5 mm) structure is reported. The BaFe12O19 film had strong in-plane uniaxial anisotropy and was therefore self-biased. Upon exposure to light, a temperature difference (ΔT) was established across the BaFe12O19 thickness that gave rise to a pure spin current in the Pt via the spin Seebeck effect. Via the inverse spin Hall effect, the spin current produced an electric voltage across one of the Pt lateral dimensions. The voltage varied with time in the same manner as ΔT and flipped its sign when the magnetization in BaFe12O19 was reversed.