A classical mechanism for negative magnetoresistance in two-dimensional systems in the ballistic regime

TL;DR

This paper proposes a classical ballistic transport mechanism in ultra-high mobility 2D systems that explains the temperature-independent negative magnetoresistance observed in experiments, emphasizing the role of edge scattering and inter-particle interactions.

Contribution

It introduces a novel classical mechanism for negative magnetoresistance in 2D systems within the ballistic regime, highlighting the effects of inter-particle scattering and magnetic fields.

Findings

Inter-particle scattering leads to positive hydrodynamic corrections to conductance.

Weak magnetic fields induce negative magnetoresistance through a classical ballistic mechanism.

The mechanism explains the temperature-independent part of observed giant negative magnetoresistance.

Abstract

In ultra-high quality two-dimensional (2D) materials the mean free paths of phonons and electrons relative to all mechanisms of scattering can be much greater than a size of a sample. In this case the most intensive type of scattering of particles is their collisions with sample edges and the ballistic regime of heat and charge transport is realized. We study the ballistic transport of classical interacting 2D particles in a long narrow sample. We show that the inter-particle scattering conserving momentum leads to a positive hydrodynamic correction to the ballistic conductance, which is a precursor of the viscous Poiseuille flow. We examine the effect of weak magnetic field on the electron ballistic conductance and predict a novel classical ballistic mechanism for negative magnetoresistance. Our analysis demonstrates that, apparently, such mechanism explains the temperature-independent part of the giant negative magnetoresistance recently observed in the ultra-high mobility GaAs quantum wells.