Magnetoresistivity in MgB2 as a probe of disorder in p- and s-bands

TL;DR

This study investigates how disorder affects the magnetoresistivity of MgB2 thin films, revealing changes in scattering times in p- and s-bands due to irradiation and doping, which enhances understanding of multiband transport in superconductors.

Contribution

It provides a quantitative analysis of disorder effects on scattering times in p- and s-bands of MgB2, using magnetoresistivity measurements in epitaxial thin films.

Findings

Disorder increases in both bands with irradiation and doping.

Undoped films have smaller p-band scattering times compared to s-bands.

Highly irradiated and C-doped samples show similar scattering times in both bands.

Abstract

In this paper we present normal state magnetoresistivity data of magnesium diboride epitaxial thin films with different levels of disorder, measured at 42K in magnetic fields up to 45 Tesla. Disorder was introduced in a controlled way either by means of neutron irradiation or by carbon doping. From a quantitative analysis of the magnetoresistivity curves with the magnetic field either parallel or perpendicular to the plane of the film, we extract the ratio of the scattering times in p- and s-bands. We demonstrate that the undoped unirradiated thin film has p scattering times smaller than s ones; upon irradiation, both bands become increasingly more disordered; eventually the highly irradiated sample (neutron fluence 7.7X1017 cm-2) and the C-doped sample have comparable scattering times in the two types of bands. This description of the effect of disorder in the two kinds of bands on transport is consistent with the residual resistivity values and with the temperature dependence of the resistivity.