Superconducting ground state of the topological superconducting candidates Ti3 X (X = Ir, Sb)

The topologically nontrivial band structure of A15 compounds has drawn a significant amount of attention owing to the possible realization of topological superconductivity. The superconducting ground state of the A15 alloys Ti3 X (X = Ir, Sb), by muon spectroscopy, has been investigated. Zero-field muon spin relaxation measurements have shown that time-reversal symmetry is preserved in these materials. Furthermore, specific-heat and transverse-field muon rotation measurements rule out any possibility of a nodal or anisotropic superconducting gap but reveal a conventional isotropic s -wave gap structure. This supports the idea that these A15 superconductors are time-reversal-symmetry-preserved topological superconducting candidate compounds.