Transition of stoichiometricSr2VO3FeAsto a superconducting state at 37.2 K

Abstract

The superconductor ${\text{Sr}}_{4}{\text{V}}_{2}{\text{O}}_{6}{\text{Fe}}_{2}{\text{As}}_{2}$ with transition temperature at 37.2 K was successfully fabricated. It has a layered structure with the space group of $p4/nmm$ and with the lattice constants $a=3.9296\text{ }\text{\AA{}}$ and $c=15.6732\text{ }\text{\AA{}}$. The observed large diamagnetization signal and zero resistance demonstrated the bulk superconductivity. The broadening of resistive transition was measured under different magnetic fields revealing a rather high upper critical field. The results also suggest a large vortex liquid region that reflects high anisotropy of the system. The Hall-effect measurements revealed dominantly electronlike charge carriers in this material. The superconductivity in the present system may be induced by oxygen deficiency or the multiple valence states of vanadium.