Role of interband scattering in neutron irradiated MgB2 thin films by Scanning Tunneling Spectroscopy measurements

A series of $\mathrm{Mg}{\mathrm{B}}_{2}$ 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 the local density of states of the $\ensuremath{\pi}$ band. With increasing disorder, the conductance peak moves towards higher voltages and becomes lower and broader, indicating a monotonic increase of the $\ensuremath{\pi}$ gap and of the broadening parameter. These results are discussed in the framework of two-band superconductivity.