Fully Band Resolved Scattering Rate in MgB2 Revealed by Nonlinear Hall Effect and Magnetoresistance Measurements

TL;DR

This study measures the temperature-dependent scattering rates in MgB2 thin films using nonlinear Hall effect and magnetoresistance, revealing how disorder affects multiband scattering in this superconductor.

Contribution

It introduces a novel method combining experimental measurements and theoretical modeling to determine band-specific scattering rates in MgB2.

Findings

Scattering rates vary with temperature and disorder levels.

Nonlinear Hall effect and magnetoresistance decrease with increasing disorder.

First direct derivation of multiband scattering rates in MgB2.

Abstract

We have measured the normal state temperature dependence of the Hall effect and magnetoresistance in epitaxial MgB2 thin films with variable disorders characterized by the residual resistance ratio RRR ranging from 4.0 to 33.3. A strong nonlinearity of the Hall effect and magnetoresistance have been found in clean samples, and they decrease gradually with the increase of disorders or temperature. By fitting the data to the theoretical model based on the Boltzmann equation and ab initio calculations for a four-band system, for the first time, we derived the scattering rates of these four bands at different temperatures and magnitude of disorders. Our method provides a unique way to derive these important parameters in multiband systems.