Single-gap superconductivity in Mo$_8$Ga$_{41}$

TL;DR

This study investigates whether Mo$_8$Ga$_{41}$ exhibits two-gap superconductivity, using thermodynamic and spectroscopic methods, and finds evidence supporting a single-gap, strongly coupled superconducting state.

Contribution

The paper provides detailed experimental evidence that Mo$_8$Ga$_{41}$ is a single-gap superconductor, clarifying previous ambiguous reports of multigap behavior.

Findings

Only one intrinsic superconducting gap detected

Strong electron-phonon coupling in Mo$_8$Ga$_{41}$

Traces of multiple phases may mimic multigap features

Abstract

In this paper, potential two-gap superconductivity in Mo$_8$Ga$_{41}$ is addressed in detail by means of thermodynamic and spectroscopic measurements. Combination of highly sensitive ac-calorimetry and scanning tunneling spectroscopy (STS), as bulk and surface sensitive probes, utilized on the same piece of crystal reveals that there is only one intrinsic gap in the system featuring strong electron-phonon coupling. Traces of multiple superconducting phases seen by STS and also in the heat capacity measured in high magnetic fields on a high-quality and seemingly single-phase crystal might mimic the multigap superconductivity of Mo$_8$Ga$_{41}$ suggested recently in several studies.