Superconductivity and topological aspects of the rocksalt carbides NbC and TaC

Abstract

Superconducting materials with a nontrivial band structure are promising candidates in the search for topological superconductivity. The rocksalt carbides NbC and TaC are two fully gapped superconductors with relatively high critical temperatures (${T}_{c}$ = 11.0 and 10.3 K, respectively). They exhibit three closed node lines in the bulk band structure protected by time-reversal and space-inversion symmetry. By combining muon spin rotation and relaxation investigations with theoretical calculations, the authors demonstrate that rocksalt NbC is a potential topological superconductor.