  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 = (1/8,1/8,0). The
ordered moment of ~ 0.1 muB 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 recover the typical quasi-nested Fermi-surface even without magnetic moment.
From this we suggest 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 clearly reveal that Sr2VO3FeAs is a typical
iron-arsenide superconductor with quasi-nested hole- and electron-like Fermi
surface sheets, and constitutes no new paradigm. We suggest that intrinsic
electron-doping through V3+/V4+ mixed valence is responsible for the absence of
SDW ordering.
