Intraband versus interband scattering rate effects in neutron irradiated MgB2

TL;DR

This paper investigates how intraband and interband scattering affect the superconducting properties of MgB2 under neutron irradiation, revealing that intraband effects become significant at higher disorder levels, challenging previous theories.

Contribution

It introduces the importance of intraband electron lifetime effects in understanding superconductivity suppression in irradiated MgB2, beyond interband scattering predictions.

Findings

Interband scattering alone does not explain Tc suppression at high disorder.

Intraband electron lifetime effects are crucial at higher disorder levels.

Superconductivity suppression involves a combination of scattering mechanisms.

Abstract

One of the most important predictions of the two-gap theory of superconductivity concerns the role of interband scattering (IBS) by impurities. IBS is expected to decrease the critical temperature, Tc, of MgB2 to a saturation value of about 20 K, where the two gaps merge to a single one. These predictions have been partially contradicted by experiments. In fact, Tc does not saturate in irradiated samples, but decreases linearly with residual resistivity and the merging of the gaps has been observed at a much lower Tc (11 K). In this paper we argue that, while at low level of disorder IBS is the leading mechanism that suppresses superconductivity, at higher disorder the experimental results can only be understood if the smearing of the density of states due to intraband electron lifetime effects is considered.