Nonmonotonic magnetoresistance of a two-dimensional viscous electron-hole fluid in a confined geometry

TL;DR

This paper investigates the non-monotonic magnetoresistance behavior in a two-dimensional viscous electron-hole fluid confined in nanostructures, revealing a transition from negative to positive and linear magnetoresistance at high fields.

Contribution

It introduces the concept of non-monotonic magnetoresistance as a signature of viscous electron-hole fluid flow in confined geometries, considering mutual friction effects.

Findings

Magnetoresistance changes sign from negative to positive with increasing magnetic field.

At very high fields, magnetoresistance becomes linear.

Mutual friction between electrons and holes significantly influences flow behavior.

Abstract

Ultra-pure conductors may exhibit hydrodynamic transport where the collective motion of charge carriers resembles the flow of a viscous fluid. In a confined geometry (e.g., in ultra-high quality nanostructures) the electronic fluid assumes a Poiseuille-like flow. Applying an external magnetic field tends to diminish viscous effects leading to large negative magnetoresistance. In two-component systems near charge neutrality the hydrodynamic flow of charge carriers is strongly affected by the mutual friction between the two constituents. At low fields, the magnetoresistance is negative, however at high fields the interplay between electron-hole scattering, recombination, and viscosity results in a dramatic change of the flow profile: the magnetoresistance changes its sign and eventually becomes linear in very high fields. This novel non-monotonic magnetoresistance can be used as a fingerprint to detect viscous flow in two-component conducting systems.