Ir 5d-band derived superconductivity in LaIr3

The superconducting properties of rhombohedral LaIr3 were examined using susceptibility, resistivity, heat capacity, and zero-field (ZF) and transverse-field (TF) muon spin relaxation and rotation (SR) measurements. The susceptibility and resistivity measurements confirm a superconducting transition below K. Two successive transitions are observed in the heat capacity data, one at K and a second at 1.2 K below . The heat capacity jump is , which is lower than 1.43 expected for Bardeen-Cooper-Schrieffer (BCS) weak-coupling limit. TF-SR measurements reveal a fully gapped s-wave superconductivity with , which is small compared to the BCS value of 3.56, suggesting weak-coupling superconductivity. The magnetic penetration depth, , estimated from TF-SR gives nm, a superconducting carrier density carriers m(-3) and a carrier effective-mass enhancement factor . ZF-SR data show no evidence for any spontaneous magnetic fields below , which demonstrates that time-reversal symmetry is preserved in the superconducting state of LaIr3.