Superconducting and critical properties of PrOFe0.9Co0.1As: effect of P   doping
  PrOFe0.9Co0.1As is known to be a superconductor with a TC of ~14 K. 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 PrOFe0.9Co0.1As1-xPx (P doping at As sites). All the compounds crystallize in the tetragonal ZrCuSiAs type structure (space group = P4/nmm). The lattice parameters (a and c) decrease as expected on substitution of smaller phosphorous at the arsenic site in PrOFe0.9Co0.1As 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 was 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 indicate a low value of ~40 meV and show no significant variation with P substitution. 
Shilpam Sharma, Jai Prakash, Gohil S. Thakur, A. T. Satya, A.   Bharathi, A K Ganguli and C S Sundar
cond-mat.supr-con cond-mat.str-el