Electronic structures of Fe 3 − x M x O 4 ( M = Mn , Zn ) spinel oxide thin films investigated by x-ray photoemission spectroscopy and x-ray magnetic circular dichroism

We fabricated ${\mathrm{Fe}}_{3\ensuremath{-}x}{M}_{x}{\mathrm{O}}_{4}$ $(M=\mathrm{Mn},\mathrm{Zn})$ thin film by pulsed laser deposition technique and investigated their electronic structure by hard x-ray photoemission spectroscopy (HX-PES) and x-ray magnetic circular dichroism (XMCD). HX-PES and XMCD revealed that the solid solution system of ${\mathrm{Fe}}_{3\ensuremath{-}x}{M}_{x}{\mathrm{O}}_{4}$ $(M=\mathrm{Mn},\mathrm{Zn})$ is the best candidate for tunable ferromagnetic oxide semiconductor judging from systematic change of Fe, Mn core-level spectra, and valence band spectra by substitution. We present a model to explain modulation of electric and magnetic properties and electronic structure evolution caused by strongly correlated electron.