Heating process in the pre-Breakdown regime of the Quantum Hall Efect : a size dependent effect

TL;DR

This study investigates how the size of Hall bar samples influences heating phenomena in the pre-breakdown regime of the quantum Hall effect, revealing size-dependent electric field domain formation near contacts.

Contribution

It provides experimental evidence that sample width affects heating and electric field domain formation before quantum Hall breakdown, especially in samples narrower than 400 microns.

Findings

Sample size influences pre-breakdown heating effects.

High electric field domains are observed only in narrower samples.

Critical currents vary with filling factor and sample dimensions.

Abstract

Our study presents experimental measurements of the contact and longitudinal voltage drops in Hall bars, as a function of the current amplitude. We are interested in the heating phenomenon which takes place before the breakdown of the quantum Hall effect, i.e. the pre-breakdown regime. Two types of samples has been investigated, at low temperature (4.2 and 1.5K) and high magnetic field (up to 13 T). The Hall bars have several different widths, and our observations clearly demonstrate that the size of the sample influences the heating phenomenon. By measuring the critical currents of both contact and longitudinal voltages, as a function of the filling factor (around $i=2$), we highlight the presence of a high electric field domain near the source contact, which is observable only in samples whose width is smaller than 400 microns.