Transport Properties of Clean Quantum Point Contacts

TL;DR

This paper investigates how electron-electron interactions and disorder affect quantum point contacts, using high-mobility heterostructures to reveal intrinsic transport features and confinement potential parameters.

Contribution

It introduces novel growth techniques for high-mobility samples, enabling detailed analysis of the confinement potential in clean quantum point contacts.

Findings

Transport features obscured by disorder are revealed in high-mobility samples.

Parameters of the confinement potential are extracted from transport data.

Understanding the potential shape aids in predicting interaction-induced states.

Abstract

Quantum point contacts are fundamental building blocks for mesoscopic transport experiments and play an important role in recent interference- and fractional quantum Hall experiments. However, it is not clear how electron-electron interactions and the random disorder potential influence the confinement potential and give rise to phenomena like the mysterious 0.7 anomaly. Novel growth techniques of GaAs/AlGaAs heterostructures for high-mobility two-dimensional electron gases enable us to investigate quantum point contacts with a strongly suppressed disorder potential. These clean quantum point contacts indeed show transport features that are obscured by disorder in standard samples. From this transport data, we are able to extract the parameters of the confinement potential which describe its shape in longitudinal and transverse direction. Knowing the shape (and hence the slope) of the confinement potential might be crucial to predict which interaction-induced states can form in quantum point contacts.