Non-linear Transport Phenomena and Current-induced Hydrodynamics in Ultra-high Mobility Two-dimensional Electron Gas

TL;DR

This study explores non-linear transport and current-induced hydrodynamics in an ultra-high mobility 2D electron gas, revealing phase diagrams of phenomena and the suppression of electron-electron scattering with DC current.

Contribution

It demonstrates a novel method of inducing hydrodynamics via DC current and provides detailed phase diagrams of transport phenomena in ultra-high mobility 2DEGs.

Findings

Identification of distinct transport regimes via resistivity maps.

Suppression of electron-electron scattering length with increasing DC current.

Observation of high-order HIRO peaks and unexpected features.

Abstract

We report on non-linear transport phenomena at high filling factor and DC current-induced electronic hydrodynamics in an ultra-high mobility (mu=20x10^6 cm^2/Vs) two-dimensional electron gas in a narrow (15 micron wide) GaAs/AlGaAs Hall bar for DC current densities reaching 0.67 A/m. The various phenomena and the boundaries between the phenomena are captured together in a two-dimensional differential resistivity map as a function of magnetic field (up to 250 mT) and DC current. This map, which resembles a phase diagram, demarcate distinct regions dominated by Shubnikov-de Haas (SdH) oscillations (and phase inversion of these oscillations) around zero DC current; negative magnetoresistance and a double-peak feature (both ballistic in origin) around zero field; and Hall field-induced resistance oscillations (HIROs) radiating out from the origin. From a detailed analysis of the data near zero field, we show that increasing the DC current suppresses the electron-electron scattering length that drives a growing hydrodynamic contribution to both the differential longitudinal and transverse (Hall) resistivities. Our approach to induce hydrodynamics with DC current differs from the more usual approach of changing the temperature. We also find a significant (factor of two to four) difference between the quantum lifetime extracted from SdH oscillations, and the quantum lifetime extracted from HIROs. In addition to observing HIRO peaks up to the seventh order, we observe an unexpected HIRO-like feature close to mid-way between the first-order and the second-order HIRO maxima at high DC current.