Investigation of superconducting gap structure in HfIrSi using muon spin relaxation/rotation.

We have investigated the superconducting state of HfIrSi using magnetization, specific heat, muon spin rotation and relaxation ([Formula: see text]SR) measurements. Superconductivity was observed at [Formula: see text] K in both specific heat and magnetization measurements. From an analysis of the transverse-field [Formula: see text]SR data, it is clear that the temperature variation of superfluid density is well fitted by an isotropic Bardeen-Cooper-Schrieffer (BCS) type s-wave gap structure. The superconducting carrier density [Formula: see text] m -3