Evidence for Scattering-Dependent Multigap Superconductivity in Ba8Si46

TL;DR

This study uses tunneling spectroscopy to reveal multigap superconductivity in Ba8Si46, showing a dominant gap and a smaller induced gap caused by inter-band scattering, indicating complex multiband behavior.

Contribution

It provides direct experimental evidence of multigap superconductivity in Ba8Si46 with scattering-dependent gaps, a novel insight into its electronic structure.

Findings

Two distinct energy gaps identified: DeltaL = 1.3meV and DeltaS = 0.9meV.

DeltaL is the main superconducting gap, while DeltaS is induced by inter-band scattering.

The smaller gap is dispersive and linked to a non-superconducting band.

Abstract

We have studied the quasiparticle excitation spectrum of the superconductor Ba8Si46 by local tunneling spectroscopy. Using high energy resolution achieved in Superconductor-Superconductor junctions we observed tunneling conductance spectra of a non-conventional shape revealing two distinct energy gaps, DeltaL = 1.3meV and DeltaS = 0.9meV. The analysis of tunneling data evidenced that DeltaL is the principal superconducting gap while DeltaS, smaller and more dispersive, is induced into an intrinsically non-superconducting band of the material by the inter-band quasiparticle scattering.