# Superconducting and normal state properties of noncentrosymmetric superconductor NbOs$_{2}$ investigated by muon spin relaxation and rotation

## TL;DR

This study investigates NbOs₂, a noncentrosymmetric superconductor, revealing it is a weakly coupled, fully gapped superconductor that preserves time-reversal symmetry, with electronic properties near the boundary of unconventional superconductivity.

## Contribution

It provides the first comprehensive experimental analysis of NbOs₂'s superconducting properties, highlighting its conventional behavior despite proximity to unconventional regimes.

## Key findings

- NbOs₂ is a weakly coupled type-II superconductor.
- Time-reversal symmetry is preserved in the superconducting state.
- Electronic properties suggest proximity to unconventional superconductivity.

## Abstract

Noncentrosymmetric superconductors with $\alpha$-manganese structure has attracted much attention recently, after the discovery of time-reversal symmetry breaking in all the members of Re$_{6}$X (X = Ti, Hf, Zr) family. Similar to Re$_{6}$X, NbOs$_{2}$ also adopts $\alpha$-$Mn$ structure and found to be superconducting with critical temperature $T_{c}$ $\approx$ 2.7 K. The results of the resistivity, magnetization, specific heat and muon-spin relaxation/rotation measurements show that NbOs$_{2}$ is a weakly coupled type-II superconductor. Interestingly, the zero-field muon experiments indicate that the time-reversal symmetry is preserved in the superconducting state. The low-temperature transverse-field muon measurements and the specific heat data evidence a conventional isotropic fully gapped superconductivity. However, the calculated electronic properties in this material show that the NbOs$_{2}$ is positioned close to the band of unconventionality of the Uemura plot, indicating that NbOs$_{2}$ potentially borders an unconventional superconducting ground state.