Non-monotonic change of electronic properties by As substitution in LaFeP(O,F)

Abstract

The discovery of superconductivity at 28K in fluorine doped LaFeAsO stimulated a great interest in iron arsenide superconductors. But many differences of physical properties exist between FeP and FeAs 1111 oxypnictide superconductors. To reveal its origin, we synthesized LaFeP1−xAsxO0.9F0.1, and investigated the x-dependence of the physical properties. In contrast to a monotonic change of lattice parameters, Tc and T-dependence of resistivity show non-monotonic change.