Unconventional superconductivity in a non-centrosymmetric ${\alpha}$-Mn alloy NbTaOs$_{2}$

TL;DR

This study synthesizes and investigates the unconventional superconducting properties of the non-centrosymmetric alloy NbTaOs₂, revealing evidence of time-reversal symmetry breaking and a fully-gapped superconducting state through various experimental techniques.

Contribution

It is the first comprehensive experimental investigation of NbTaOs₂, demonstrating its unconventional superconductivity and symmetry-breaking features.

Findings

Evidence of a fully-gapped superconducting state.

Detection of time-reversal symmetry breaking.

Confirmation of moderate coupling in superconductivity.

Abstract

Non-centrosymmetric superconductors have emerged as a fascinating avenue for exploring unconventional superconductivity. Their broken inversion and time-reversal symmetries make them prime candidates for realizing the intrinsic superconducting diode effect (SDE). In this work, we synthesize the ternary non-centrosymmetric $\alpha$-Mn alloy NbTaOs$_{2}$ and conduct a comprehensive investigation of its superconducting properties through resistivity, magnetization, specific heat and muon spin rotation/relaxation ($\mu$SR) techniques. Our transverse field-$\mu$SR and specific heat results provide evidence of a moderately coupled, fully-gaped superconducting state. Zero field-$\mu$SR measurements reveal a subtle increase in the relaxation rate below the transition temperature, suggesting time reversal symmetry breaking in the superconducting ground state of NbTaOs$_{2}$.