Role of interband scattering in neutron irradiated MgB$_2$ thin films by Scanning Tunneling Spectroscopy measurements

TL;DR

This study investigates how neutron irradiation-induced disorder affects the superconducting gaps in MgB$_2$ thin films using scanning tunneling spectroscopy, revealing an increase in the $\pi$ gap and broadening with disorder.

Contribution

It provides experimental insights into the role of interband scattering in MgB$_2$ superconductors under neutron irradiation, using local density of states measurements.

Findings

The $\pi$ gap increases monotonically with disorder.

Conductance peaks shift to higher voltages and broaden.

Results support two-band superconductivity models.

Abstract

A series of MgB$_2$ thin films systematically disordered by neutron irradiation have been studied by Scanning Tunneling Spectroscopy. The c-axis orientation of the films allowed a reliable determination of local density of state of the $\pi$ band. With increasing disorder, the conductance peak moves towards higher voltages and becomes lower and broader, indicating a monotonic increase of the $\pi$ gap and of the broadening parameter. These results are discussed in the frame of two-band superconductivity.