Control of Correlations in Sr4V2O6Fe2As2 by Chemical Stoichiometry

Abstract

We show using a combination of powder X-ray and neutron diffraction, first principles calculations, temperature- and field-dependent magnetization, heat capacity and resistivity data that the superconducting behavior of `Sr${}_4$V${}_2$O${}_6$Fe${}_2$As${}_2$' is dependent on synthesis conditions, particularly, heating profiles result in unintentional chemical doping. This compound can be tuned from a state in which the vanadium electrons are itinerant with a high electronic density of states, to a state where the vanadium-oxide layers are insulating and presumably antiferromagnetic.

9 pages, 10 figures, submitted to Phys. Rev. B