Transport anomalies due to anisotropic interband scattering

TL;DR

This paper investigates how anisotropic interband scattering in multiband systems causes unusual transport phenomena like negative magnetoresistance and Hall coefficient extrema, revealing the impact of Fermi surface mismatch.

Contribution

It demonstrates that anisotropic scattering can lead to negative transport times and anomalous transport effects beyond the relaxation-time approximation.

Findings

Anisotropic scattering causes negative transport times.

Negative magnetoresistance observed due to anisotropic scattering.

Fermi surface mismatch reduces the anisotropy needed for anomalies.

Abstract

Unexpected transport behavior can arise due to anisotropic single-particle scattering in multiband systems. Specifically, we show within a semiclassical Boltzmann approach beyond the relaxation-time approximation that anisotropic scattering between electronlike and holelike Fermi surfaces generically leads to negative transport times, which in turn cause negative magnetoresistance, an extremum in the Hall coefficient, and a reduction of the resistivity. The anisotropy required for this to occur decreases with increasing mismatch between the Fermi-surface radii.