# Two-gap superconductivity in Mo$_{8}$Ga$_{41}$ and its evolution upon the V substitution

## TL;DR

This study investigates the microscopic superconducting properties of Mo8Ga41 using muon spin rotation experiments, revealing two-gap superconductivity that is suppressed upon V substitution, leading to a single-gap state and potential competing phases.

## Contribution

The paper provides the first microscopic evidence of two-gap superconductivity in Mo8Ga41 and shows how V substitution suppresses one gap, altering the superconducting state.

## Key findings

- Two-gap superconductivity in Mo8Ga41 confirmed by μSR.
- V substitution suppresses one superconducting gap.
- Emergence of a competing state upon V doping.

## Abstract

Zero-field and transverse-field muon spin rotation/relaxation ($\mu$SR) experiments were undertaken in order to elucidate microscopic properties of a strongly-coupled superconductor Mo$_{8}$Ga$_{41}$ with $T_{\text{c}}=9.8$ K. The upper critical field extracted from the transverse-field $\mu$SR data exhibits significant reduction with respect to the data from thermodynamic measurements indicating the coexistence of two independent length scales in the superconducting state. Accordingly, the temperature-dependent magnetic penetration depth of Mo$_{8}$Ga$_{41}$ is described using the model, in which two s-wave superconducting gaps are assumed. The V for Mo substitution in the parent compound leads to the complete suppression of one superconducting gap, and Mo$_{7}$VGa$_{41}$ is well described within the single s-wave gap scenario. The reduction in the superfluid density and the evolution of the low-temperature resistivity upon the V substitution indicate the emergence of a competing state in Mo$_{7}$VGa$_{41}$ that may be responsible for the closure of one of the superconducting gaps.