Alternative routes to electron hydrodynamics

TL;DR

This paper explores new conditions under which electron hydrodynamics can occur in two-dimensional materials, broadening the scope beyond traditional requirements by considering magnetic fields and high-frequency electric fields.

Contribution

It introduces three alternative routes to achieve electron hydrodynamics, relaxing the need for frequent electron-electron collisions and expanding potential material applications.

Findings

Frequent inelastic collisions are not strictly necessary for hydrodynamic behavior.

Magnetic fields can induce hydrodynamic electron flow.

High-frequency electric fields can promote viscous electron transport.

Abstract

Viscous flow of interacting electrons in two dimensional materials features a bunch of exotic effects. A model resembling the Navier-Stokes equation for classical fluids accounts for them in the so called hydrodynamic regime. We performed a detailed analysis of the physical conditions to achieve electron hydrodynamic transport and found three new alternative routes: favouring frequent inelastic collisions, the application of a magnetic field or a high-frequency electric field. As a mayor conclusion, we show that the conventional requirement of frequent electron-electron collisions is too restrictive and, as a consequence, materials and phenomena to be described using hydrodynamics are widened. In view of our results, we discuss recent experimental evidence on viscous flow and point out alternative avenues to reduce electric dissipation in optimized devices.