Superballistic paradox in electron fluids: Evidence of tomographic transport

TL;DR

This paper investigates the superballistic conduction in electron fluids, revealing that considering electrons as fermions with tomographic dynamics explains the paradox of superballistic behavior at near-zero temperatures.

Contribution

It introduces a novel approach replacing classical dynamics with tomographic dynamics to resolve the superballistic paradox in electron hydrodynamics.

Findings

Replacing classical with tomographic dynamics enhances superballistic conduction.

The superballistic paradox is resolved by considering electrons as fermions.

The study explains differences between superballistic conduction and other effects.

Abstract

Electron hydrodynamics encompasses the exotic fluid-like behavior of electrons in two-dimensional materials such as graphene. It accounts for superballistic conduction, also known as the Gurzhi effect, where increasing temperature reduces the electrical resistance. In analogy with conventional fluids, the Gurzhi effect is only expected in the hydrodynamic regime, with the decrease in the resistance occurring at intermediate temperatures. Nonetheless, experiments on electron fluids consistently show that superballistic conduction starts at close-to-zero temperatures. To address this paradox, we study hydrodynamic flow, and we find that replacing the classical dynamics with tomographic dynamics, where only head-on collisions are allowed between electrons, solves the dilemma. The latter strengthens superballistic conduction, with potential applications in low-dissipation devices, and explains its differences with the Molenkamp effect and conventional fluids dynamics. Our study reveals that the superballistic paradox is resolved by considering the electrons not as classical particles but as fermions.