Hydrodynamics, viscous electron fluid, and Wiedeman-Franz law in 2D semiconductors

TL;DR

This paper theoretically investigates hydrodynamic electron behavior in 2D semiconductors, predicting conditions under which collective effects dominate and cause violations of the Wiedeman-Franz law, especially in high-mobility GaAs systems.

Contribution

It identifies 2D GaAs as an ideal platform for observing hydrodynamic electron effects and predicts a violation of the Wiedeman-Franz law in bulk transport properties.

Findings

High-mobility 2D GaAs exhibits strong hydrodynamic effects.

Predicted violation of Wiedeman-Franz law at modest mobilities.

Hydrodynamic effects observable in bulk transport, not just narrow systems.

Abstract

Considering theoretically the transition between hydrodynamic and ballistic regimes in 2D semiconductors, we show that electrons in high-mobility 2D GaAs are by far the best system for the direct observation of collective hydrodynamic effects even in bulk transport properties independent of complicated transport features in narrow constrictions and small systems where Gurzhi phenomena are typically studied experimentally. We predict a strong hydrodynamics-induced generic violation of the Wiedeman-Franz law in bulk 2D GaAs systems for mobilities as modest as $10^6 \mathrm{cm}^2/Vs$ and densities $1$-$5\times10^{11} \mathrm{cm}^{-2}$ in the temperature range of $T=1$-$40K$.