Scanning Gate Microscopy in a Viscous Electron Fluid

TL;DR

This study uses scanning gate microscopy to explore viscous electron flow in a Ga[Al]As heterostructure, revealing temperature-dependent transport regimes and confirming theoretical models for electron liquids.

Contribution

It demonstrates the ability to distinguish ballistic and viscous electron transport regimes in Ga[Al]As using scanning gate microscopy, expanding understanding beyond graphene systems.

Findings

Viscous effects become prominent at higher temperatures.

Scanning gate images differentiate transport regimes.

Good agreement with recent electron liquid theories.

Abstract

We measure transport through a Ga[Al]As heterostructure at temperatures between 0.1 K and 30 K. Increasing the temperature enhances the electron-electron scattering rate and viscous effects in the two-dimensional electron gas arise. To probe this regime we measure so-called vicinity voltages and use a voltage-biased scanning tip to induce a movable local perturbation. We find that the scanning gate images differentiate reliably between the different regimes of electron transport. Our data are in good agreement with recent theories for interacting electron liquids in the ballistic and viscous regimes stimulated by measurements in graphene. However, the range of temperatures and densities where viscous effects are observable in Ga[Al]As are very distinct from the graphene material system.