Local breakdown of the quantum Hall effect in narrow single layer graphene Hall devices

TL;DR

This study investigates the local breakdown mechanisms of the quantum Hall effect in narrow monolayer graphene devices, revealing impurity-mediated scattering as a key factor and highlighting spatial variability in breakdown behavior.

Contribution

It provides new insights into the local breakdown processes of the quantum Hall effect in graphene, emphasizing the role of impurities and spatial inhomogeneity.

Findings

Hall resistance remains quantized up to high current densities

Breakdown involves impurity-mediated inter-Landau level scattering

Spatial variation affects the breakdown behavior

Abstract

We have analyzed the breakdown of the quantum Hall effect in 1 micrometer wide Hall devices fabricated from an exfoliated monolayer graphene transferred on SiOx. We have observed that the deviation of the Hall resistance from its quantized value is weakly dependent on the longitudinal resistivity up to current density of 5 A/m, where the Hall resistance remains quantized even when the longitudinal resistance increases monotonously with the current. Then a collapse in the quantized resistance occurs while longitudinal resistance keeps its gradual increase. The exponential increase of the conductivity with respect to the current suggests impurity mediated inter-Landau level scattering as the mechanism of the breakdown. The results are interpreted as the strong variation of the breakdown behavior throughout the sample due to the randomly distributed scattering centers that mediates the breakdown.