Unoccupied Electronic State at Low Temperature of SrTiO3-delta Probed by Resonant Inverse Photoemission Spectroscopy

Abstract

The unoccupied electronic structure at low temperature of SrTiO3-delta has been studied by resonant-inverse photoemission spectroscopy (RIPES). The RIPES spectra show two peaks whose the energy separations match with the t2g- and eg-subbands of unoccupied Ti 3d state. A new peak clarified by the Ti 3p - 3d resonance effect is observed at 6.1 eV above Fermi level (EF). The 6.1 eV peak is not found in the O ls X-ray absorption spectrum, which reflects the electronic structure of the bulk state. The existence of the 6.1 eV peak suggests the correlation effect at low temperature of SrTiO3.