Manifestations of classical size effect and electronic viscosity in the magnetoresistance of narrow two-dimensional conductors: Theory and experiment

TL;DR

This paper combines theory and experiment to analyze how classical size effects and electronic viscosity influence magnetoresistance in narrow 2D conductors, revealing temperature-dependent features linked to electron interactions.

Contribution

It introduces a classical kinetic theory for magnetotransport in narrow 2D channels and correlates it with experimental data, highlighting the role of electronic viscosity and size effects.

Findings

Identification of a slope change in magnetoresistance derivative at specific cyclotron diameters

Observation of suppression of size effect features with increasing temperature

Determination of electron-electron scattering relaxation time from combined analysis

Abstract

We develop a classical kinetic theory of magnetotransport of 2D electrons in narrow channels with partly diffusive boundary scattering and apply it to description of magnetoresistance measured in the temperature interval 4.2-30 K in long mesoscopic bars fabricated from high-purity GaAs quantum well structures. Both experiment and theory demonstrate a number of characteristic features in the longitudinal and Hall resistances caused by the size effect in two dimensions owing to the high ballisticity of the transport. In addition to the features described previously, we also reveal a change in the slope of the first derivative of magnetoresistance when the cyclotron orbit diameter equals to half of the channel width. These features are suppressed with increasing temperature as a result of the electronic viscosity due to electron-electron interaction. By comparing theory and experiment, we determine the characteristic time of relaxation of angular distribution of electrons caused by electron-electron scattering.