Superconducting and critical properties of PrOFe0.9Co 0.1As: Effect of P doping

摘要

PrOFe0.9Co0.1As is known to be a superconductor with a TC of ～ 14K. In an attempt to induce charge transfer and also induce chemical pressure between the FeAs and PrO layers we have synthesized for the first time oxypnictides of the type PrOFe0.9Co 0.1As1 - xPx (P doping at As sites). All the compounds crystallize in the tetragonal ZrCuSiAs-type structure (space group = P4mm). The lattice parameters (a and c) decrease as expected on substitution of smaller phosphorus at the arsenic site in PrOFe0.9Co 0.1As and a decrease in TC was observed on substitution of P ions at a low rate of 0.13K/at.% of P for x > 0.1. The irreversibility field (Hirr) and critical current density (JC), obtained using the AC susceptibility measurements, were found to decrease monotonically with increasing P concentration. Hirr is observed to be much smaller than HC2, pointing to a very low pinning energy. The pinning potential obtained using both in-field transport and AC susceptibility measurements indicates a low value of ～ 40meV and shows no significant variation with P substitution.