Resonant Soft-X-Ray Emission as a Bulk Probe of Correlated Electron Behavior in Metallic SrxCa1-xVO3

The evolution of electron correlation in SrxCa1-xVO3 has been studied using a combination of bulk-sensitive resonant soft x-ray emission spectroscopy, surface-sensitive photoemission spectroscopy, and ab initio band structure calculations. We show that the effect of electron correlation is enhanced at the surface. Strong incoherent Hubbard subbands are found to lie similar to 20% closer in energy to the coherent quasiparticle features in surface-sensitive photoemission spectroscopy measurements compared with those from bulk-sensitive resonant soft x-ray emission spectroscopy, and a similar to 10% narrowing of the overall bandwidth at the surface is also observed.