Possible magnetic order and suppression of superconductivity by V doping in Sr2VO3FeAs

Superconductivity at 33 K in Sr2VO3FeAs is completely suppressed by small amounts of V doping in Sr2VO3(Fe0.93(+/- 0.01)V0.07(+/- 0.01))As. The crystal structures and exact stoichiometries are determined by combined neutron powder diffraction and x-ray powder diffraction. Sr2VO3FeAs is shown to be very sensitive to Fe/V mixing, which interferes with or even suppresses superconductivity. This inhomogeneity may be intrinsic and explains scattered reports regarding T-c and reduced superconducting phase fractions in Sr2VO3FeAs. Neutron-diffraction data collected at 4 K indicate incommensurate magnetic ordering of the V sublattice with a propagation vector q approximate to(0,0,0.306). This suggests strongly correlated vanadium, which does not contribute significantly to the Fermi surface of Sr2VO3FeAs