Transparent spin thermoelectricity with enhanced energy conversion

Spin-thermoelectrics (STE) allows energy harvesting from the waste heat through the orthogonal relationship between the charge and heat flow, which offers large area scalability. Moreover, STE devices can be well adapted for transparent energy harvesting when a transparent magnetic insulator is exploited as a spin current source. Nevertheless, the transparent characteristics of STE devices have not been studied extensively so far. In this study, we show transparent characteristics of STE device based on thin films of Yttrium Iron Garnet (YIG)/Pt bilayers. Decreasing thickness of the Pt layer not only improves transmittance of visible light but simultaneously enhances the STE performance. The fabricated STE device of YIG (20 nm)/Pt (0.8 nm) exhibits a longitudinal spin Seebeck coefficient, S_LSSE ≈ 7.04 μV/K, while sustaining over 80% transparency at λ = 700 nm. Our study shows the potential usage of STE as an alternative transparent energy harvesting, which could be adapted in various multi-purpose coatings.