Origin of the zero-resistance anomaly in heavy fermion superconducting CeIrIn5:: A clue from magnetic-field and Rh-doping studies -: art. no. 220504

We present the results of the specific heat and ac magnetic susceptibility measurements of CeIr1-xRhxIn5 for x from 0 to 0.5. As x is increased from zero both quantities reflect the competition between two effects. The first is a suppression of superconductivity below the bulk transition temperature of T-c = 0.4 K, which is due to the pair breaking, effect of Rh impurities. The second is an increase in the volume fraction of the superconducting regions above T-c, which we attribute to defect-induced strain. Analysis of the H-T phase diagram for CeIrIn5 obtained from the bulk probes and resistance measurements points to the filamentary origin of the inhomogeneous superconductivity at T(rho)approximate to1.2 K, where the resistance drops to zero. The identical anisotropies in the magnetic field dependence of the specific heat and the resistance anomalies in CeIrln(5) indicate that the filamentary superconductivity is intrinsic, involving electrons from the part of the Fermi surface responsible for bulk superconductivity.