We combined photoelectron spectroscopy with first-principles calculations to investigate electronic properties of ${\mathrm{SrTiO}}_3$ doped with Ni impurities. High-quality epitaxial pristine ${\mathrm{SrTiO}}_3$ and ${\mathrm{SrTiO}}_3$:${\mathrm{Ni}}_x$ films with $x=0.06$ and 0.12 were prepared by pulsed laser deposition. Electronic band structure calculations for the ground state, as well as one-step model photoemission calculations, which were obtained by means of the Korringa-Kohn-Rostoker Green's function method, predict the formation of localized $3d$-impurity bands in the band gap of ${\mathrm{SrTiO}}_3$ close to the valence band maxima. The measured valence bands at the resonance Ni $2p$ excitation and band dispersion confirm these findings.

• Received 11 March 2021
• Revised 6 September 2021
• Accepted 4 October 2021

DOI:https://doi.org/10.1103/PhysRevB.104.165129

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