Enhanced electron correlations at the SrxCa1-xVO3 surface

TL;DR

This study uses hard x-ray photoemission spectroscopy to investigate how electron correlations in SrxCa1-xVO3 vary between surface and bulk, revealing enhanced correlations at the surface through spectral analysis.

Contribution

It demonstrates that V 3d Hubbard bands exhibit increased correlation effects at the surface compared to the bulk in SrxCa1-xVO3, using bulk-sensitive spectroscopy and ab initio calculations.

Findings

Higher correlation at the surface than in the bulk.

Evolution of Hubbard bands with Sr content.

Good agreement between measurements and calculations.

Abstract

We report hard x-ray photoemission spectroscopy measurements of the electronic structure of the prototypical correlated oxide SrxCa1-xVO3. By comparing spectra recorded at different excitation energies, we show that 2.2 keV photoelectrons contain a substantial surface component, whereas 4.2 keV photoelectrons originate essentially from the bulk of the sample. Bulk-sensitive measurements of the O 2p valence band are found to be in good agreement with ab initio calculations of the electronic structure, with some modest adjustments to the orbital-dependent photoionization cross sections. The evolution of the O 2p electronic structure as a function of the Sr content is dominated by A-site hybridization. Near the Fermi level, the correlated V 3d Hubbard bands are found to evolve in both binding energy and spectral weight as a function of distance from the vacuum interface, revealing higher correlation at the surface than in the bulk.