A systematic study of non-ideal contacts in integer quantum Hall systems

TL;DR

This paper systematically examines how non-ideal contacts affect the chemical potential distribution and resistance measurements in integer quantum Hall systems, using simulations to replicate experimental observations.

Contribution

It introduces a comprehensive simulation approach to analyze the effects of contact geometry and barriers on quantum Hall measurements, providing insights into non-ideal contact influences.

Findings

Contact geometry significantly impacts resistance measurements.

Potential barriers alter chemical potential distribution.

Simulations replicate experimental resistance variations.

Abstract

In the present article we investigate the influence of the contact region on the distribution of the chemical potential in integer quantum Hall samples, as well as the longitudinal and Hall resistance as a function of the magnetic field. First we use a standard quantum Hall sample geometry and analyse the influence of the length of the leads where current enters/leaves the sample and the ratio of the contact width to the width of these leads. Furthermore we investigate potential barriers in the current injecting leads and the measurement arms in order to simulate non-ideal contacts. Second we simulate nonlocal quantum Hall samples with applied gating voltage at the metallic contacts. For such samples it has been found experimentally that both the longitudinal and Hall resistance as a function of the magnetic field can change significantly. Using the nonequilibrium network model we are able to reproduce most qualitative features of the experiments.