Spin injection into vanadium dioxide films from a typical ferromagnetic metal, across the metal-insulator transition of the vanadium dioxide films

A vanadium dioxide VO₂ film shows metal-insulator transition (MIT) induced by changing environmental temperature. We report the temperature dependence of electromotive force properties generated in VO₂/Ni₈₀Fe₂₀ bilayer junctions under the ferromagnetic resonance (FMR) of the Ni₈₀Fe₂₀ layer. An electromotive force generated in a VO₂/Ni₈₀Fe₂₀ bilayer junction under the FMR showed a small change across the MIT temperature of the VO₂ film, while the VO₂ film resistance drastically changed. This behavior was not only explained with the temperature dependence of the electromotive force property generated in the Ni₈₀Fe₂₀ film itself under the FMR, but also with the generated electromotive forces due to the inverse spin-Hall effect (ISHE) in the VO₂ film under the FMR of the Ni₈₀Fe₂₀ film. That is, we successfully demonstrated the spin injection from a Ni₈₀Fe₂₀ film into a VO₂ film across the MIT temperature of the VO₂ film.