Study of the superconducting ground state of topological superconducting candidates Ti$_{3}$X (X = Ir, Sb)

TL;DR

This study investigates the superconducting ground state of topological candidates Ti3X (X=Ir,Sb) using muon spectroscopy, revealing conventional s-wave pairing and preserved time-reversal symmetry, classifying them as topological superconductors.

Contribution

It provides the first microscopic evidence that Ti3X compounds are topological superconductors with a conventional s-wave gap and preserved time-reversal symmetry.

Findings

Time-reversal symmetry is preserved in Ti3X compounds.

Superconducting gap is isotropic s-wave, not nodal or anisotropic.

Classified as topological superconductors based on experimental evidence.

Abstract

The topologically non-trivial band structure of A15 compounds has drawn attention owing to the possible realization of topological superconductivity. Here, we report a microscopic investigation of the superconducting ground state in A15 compound Ti$_{3}$X (X = Ir, Sb) by muon spectroscopy measurements. Zero field muon measurements have shown that time-reversal symmetry is preserved in these materials. Furthermore, specific heat and a transverse field muon spectroscopy measurement rule out any possibility to have a nodal or anisotropic superconducting gap, revealing a conventional s-wave nature in the superconducting ground state. This work classifies A15 compound Ti$_{3}$X (X = Ir, Sb) as a time-reversal preserved topological superconductor.