# Probing the superconducting ground state of ZrIrSi: A $\mu$SR study

## TL;DR

This study investigates the superconducting properties of ZrIrSi using muon spin rotation and resistivity measurements, revealing an isotropic s-wave gap, preserved time-reversal symmetry, and strong spin-orbit coupling.

## Contribution

It provides the first muSR analysis of ZrIrSi, confirming the superconducting gap symmetry and electronic structure details through combined experimental and ab-initio calculations.

## Key findings

- Superconducting transition at 1.7 K confirmed by resistivity.
- No spontaneous magnetic field below Tc, indicating preserved TRS.
- Superfluid density fits an isotropic s-wave model with strong spin-orbit coupling.

## Abstract

The superconducting ground state of newly reported ZrIrSi is probed by means of $\mu$SR technique along with resistivity measurement. The occurrence of superconductivity at $T_\mathrm{C}$ = 1.7 K is confirmed by resistivity measurement. ZF-$\mu$SR study revealed that below $T_\mathrm{C}$, there is no spontaneous magnetic field in the superconducting state, indicates TRS is preserved in case of ZrIrSi. From TF-$\mu$SR measurement, we have estimated the superfluid density as a function of temperature, which is described by an isotropic $s-$wave model with a superconducting gap $2\Delta(0)/k_\mathrm{B}T_\mathrm{C}$ = 5.1, indicates the presence of strong spin-orbit coupling. {\it Ab-initio} electronic structure calculation indicates that there are four bands passing through the Fermi level, forming four Fermi surface pockets. We find that the low-energy bands are dominated by the $4d$-orbitals of transition metal Zr, with substantially lesser weight from the $5d$-orbitals of the Ir-atoms.