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 (≳20×106cm2/Vs) and with distinct electron density of 1.7 and 3.6×1011cm−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.
@article{arxiv.2302.12147,
title = {Anomalous Electronic Transport in High Mobility Corbino Rings},
author = {Sujatha Vijayakrishnan and F. Poitevin and Oulin Yu and Z. Berkson-Korenberg and M. Petrescu and M. P Lilly and T. Szkopek and Kartiek Agarwal and K. W. West and L. N. Pfeiffer and G. Gervais},
journal= {arXiv preprint arXiv:2302.12147},
year = {2023}
}