Temperature Dependence of Electron Viscosity in Superballistic GaAs Point Contacts

TL;DR

This study investigates how electron viscosity in GaAs point contacts varies with temperature and substrate suspension, revealing hydrodynamic behavior and enhanced electron-electron interactions in suspended structures.

Contribution

It provides experimental evidence of temperature-dependent electron viscosity and superballistic conductance in GaAs point contacts, highlighting the effects of substrate suspension on electron interactions.

Findings

Viscosity follows 1/T^2 law at low T

Viscosity follows 1/T law at higher T

Suspended PCs show reduced viscosity across all temperatures

Abstract

Electron transport in suspended and non-suspended GaAs point contacts (PCs) of different widths is experimentally studied. The superballistic contribution to the conductance, that demonstrates a distinctive quadratic dependence on the PC width and temperature growth, is extracted from the experiment. The studied PCs are shown to be described in the framework of hydrodynamic electron flow a in wide temperature range. At low temperatures, $T$, the viscosity is found out to obey the law $1/T^2$ expected for 2D systems, while at higher temperatures it has the dependence $1/T$. Similar measurements performed after the suspension of PCs, i.e. their separation from substrate, show that the electron viscosity reduces in the whole temperature range, that indicates an enhanced electron-electron interaction in suspended structures.