Electron-phonon and spin-orbit coupling in early-transition metal conductive oxides

Metallic oxides are commonly viewed as examples of electron-correlated systems, where the electron-electron interactions within narrow 3d bands govern electrical and optical properties. Among other consequences, electron effective masses are commonly found to be much enhanced compared to bare electrons and attributed to the mentioned electron correlations. However, we shall report that in some early transition metal oxides, such as SrVO₃, experimental facts –including transport and electron spectroscopic data- appear to suggest that electron-phonon coupling plays a major role on the effective mass enhancement, largely contributing to the red shift of the plasma frequency. Accordingly, plasmon excitations in these materials, would be better described as polaronic-plasmons rather than the ordinary electron-plasmons. On the other hand, in presence of large charge-lattice coupling, it can be envisaged that spin-orbit coupling could also lead to other emerging properties. In particular, we show that SrVO₃, in spite of containing light 3d¹-(V⁴⁺) cations, effectively absorbs spin currents from neighboring magnetic layers, suggesting that early transition metallic oxides may be a suitable alternative to the common heavy (and noble) metals currently used in some spintronic devices.