Electron-electron scattering and magnetoresistance of ballistic microcontacts

TL;DR

This paper models how electron-electron interactions affect conductance and magnetoresistance in ballistic microcontacts, revealing temperature-dependent corrections and magnetic field suppression effects that explain experimental anomalies.

Contribution

It introduces a semiclassical Boltzmann approach to quantify electron-electron scattering effects on conductance in 2DEG microcontacts, highlighting the role of nearly opposite momenta collisions.

Findings

Electron-electron scattering increases conductance corrections with temperature.

Magnetic fields strongly suppress these scattering-induced corrections.

The results may explain observed positive magnetoresistance anomalies.

Abstract

Using a semiclassical Boltzmann equation, we calculate corrections to the Sharvin conductance of a wide 2DEG ballistic contact that result from an electron--electron scattering in the leads. These corrections are dominated by collisions of electrons with nearly opposite momenta that come from different reservoirs. They are positive, increase with temperature, and are strongly suppressed by a magnetic field. We argue that this suppression may be responsible for an anomalous positive magnetoresistance observed in a recent experiment.