# Anomalous Electronic Transport in High Mobility Corbino Rings

## TL;DR

This study investigates anomalous low-temperature electronic transport in high-mobility GaAs/Al-GaAs Corbino rings, revealing non-monotonic resistance behavior and potential hydrodynamic effects, contrasting with conventional resistivity trends.

## Contribution

The paper presents the first observation of non-monotonic resistance behavior in high-mobility Corbino samples and explores hydrodynamic transport phenomena in these systems.

## Key findings

- Resistance decreases with temperature in low-density sample
- Resistance increases with temperature in high-density sample
- Large van der Pauw samples show monotonic resistivity behavior

## Abstract

We report low-temperature electronic transport measurements performed in two multi-terminal Corbino samples formed in GaAs/Al-GaAs two-dimensional electron gases (2DEG) with both ultra-high electron mobility ($\gtrsim 20\times 10^6$ $cm^2/Vs)$ and with distinct electron density of $1.7$ and $3.6\times 10^{11}~cm^{-2}$. In both Corbino samples, a non-monotonic behavior is observed in the temperature dependence of the resistance below 1~$K$. Surprisingly, a sharp {\it decrease} in resistance is observed with {\it increasing} temperature in the sample with lower electron density, whereas an opposite behavior is observed in the sample with higher density. To investigate further, transport measurements were performed in large van der Pauw samples having identical heterostructures, and as expected they exhibit resistivity that is monotonic with temperature. Finally, we discuss the results in terms of various lengthscales leading to ballistic and hydrodynamic electronic transport, as well as a possible Gurzhi effect.