Probing the superconducting gap structure in the noncentrosymmetric topological superconductor ZrRuAs

Abstract

The ternary transition metal pnictide ZrRuAs has been suggested to be a rare example of a superconducting topological crystalline insulator, with evidence for topological states along with bulk superconductivity below ${T}_{c}$ = 7.9 K. Here, the authors have probed the superconducting gap structure of this compound using muon-spin rotation and relaxation spectroscopy. Their results reveal a nodeless isotropic $s$-wave gap structure and confirm that time-reversal symmetry is preserved in the superconducting state of noncentrosymmetric ZrRuAs.