Superscreening by a Retroreflected Hole Backflow in Tomographic Electron Fluids

TL;DR

This paper predicts that in two-dimensional electron gases, collective free flows occur at scales smaller than the electron-electron mean free path due to retroreflected hole backflow, leading to strong potential screening and non-Fermi-liquid behavior.

Contribution

It introduces a novel mechanism of superscreening in electron fluids caused by retroreflected holes, occurring at sub-$ m extit{ell}_{ee}$ scales in a ballistic regime.

Findings

Potential exhibits a fractional power law decay $r^{-5/3}$.

Screening effects are significant at deep sub-$ m extit{ell}_{ee}$ scales.

Non-Fermi-liquid temperature dependence observed.

Abstract

Electron hydrodynamics gives rise to surprising correlated behaviors in which electrons "cooperate" to quench dissipation and reduce the electric fields needed to sustain the flow. Such collective "free" flows are usually expected at the hydrodynamic lengthscales exceeding the electron-electron scattering mean free path $\ell_{\rm ee}$. Here we predict that in two-dimensional electron gases the collective free flows actually occur at the distances much smaller than $\ell_{\rm ee}$, in a nominally ballistic regime. The sub-$\ell_{\rm ee}$ free flows arise due to retroreflected holes originating from head-on electron electron collisions, which retrace the paths of impinging electrons and cancel out their potential. An exact solution, obtained in Corbino geometry, predicts potential strongly screened by the hole backflow. Screened potential is described by a fractional power law $r^{-5/3}$ over a wide range of $r$ values, from macroscales down to deep sub-$\ell_{\rm ee}$ scales, and a distinct non-Fermi-liquid temperature dependence.