Unoccupied electronic structure in the surface state of lightly doped SrTiO3 by resonant inverse photoemission spectroscopy -: art. no. 153105

The unoccupied electronic structure in the surface state of lightly doped SrTiO3 has been studied by resonant inverse-photoemission spectroscopy (RIPES). The RIPES spectra show two features whose energy separations match the t(2g) and e(g) subbands of unoccupied Ti 3d state. A peak clarified by the Ti 3p-->3d resonance effect is observed at similar to6.1 eV above Fermi level (E-F). The similar to6.1 eV peak is not found in the O 1s x-ray absorption spectrum, which reflects the electronic structure of the bulk state. The existence of the similar to6.1 eV peak suggests the correlation effect in the surface state of lightly doped SrTiO3.