Superconducting properties of (Ba-K)Fe2As2 single crystals disordered with fast neutron irradiation

Resistivity Rho(T), Hall coefficient RH(T), superconducting transition temperature Tc and slopes of the upper critical field dHc2/dT were studied in (Ba1-xKx)Fe2As2 (x = 0.218, 0.356, 0.531) single crystals irradiated with fast neutrons. It is found that dTc/dRhoSC - the rate of decreasing Tc as a function of the RhoSC (RHoSC is the resistivity at T = Tc) - linearly increases with concentration x. Slow changes in the Hall coefficient RH, as well as the quadratic electronic contribution to the resistivity, show that there are no substantial changes in the topology of the Fermi surface caused by irradiation. The slopes of the upper critical field dHc2/dT in ab- and c-directions as a function of RHoSC determined by Hall measurements show a reasonable agreement with a model that suggests constancy of the band parameters.