Weak magnetism and the Mott state of vanadium in superconducting Sr2VO3FeAs

Abstract

We report neutron-scattering data and DFT calculations of the stoichiometric iron-arsenide superconductor Sr2VO3FeAs. Rietveld refinements of neutron powder patterns confirm the ideal composition without oxygen deficiencies. Experiments with polarized neutrons prove weak magnetic ordering in the V sublattice of Sr2VO3FeAs at ≈ 45 K with a probable propagation vector q = (18,18,0). The ordered moment of ≈ 0.1 μB is too small to remove the V 3d bands from the Fermi level by magnetic exchange splitting and much smaller than predicted from a recent LDA+U study. By using DFT calculations with a GGA+EECE functional we find the typical quasinested Fermi surface even without magnetic moment. From this we conclude that the V atoms are in a Mott state, where the electronic correlations are dominated by on-site Coulomb repulsion which shifts the V 3d states away from the Fermi energy. Our results are consistent with photoemission data and explain comprehensively why Sr2VO3FeAs is a typical iron-arsenide superconductor in spite of the partially filled V 3d shell.

Source-reported materials — not catalogue approval

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