# Magneto-exciton limit of quantum Hall breakdown in graphene

## TL;DR

This paper investigates the magneto-exciton instability as a fundamental limit to the quantum Hall effect breakdown in graphene, revealing relativistic effects and universal behavior in monolayer and bilayer graphene.

## Contribution

It demonstrates the magneto-exciton instability in monolayer graphene and links it to relativistic signatures and universal ME conductivity, extending previous bilayer graphene studies.

## Key findings

- Magneto-exciton instability observed in monolayer graphene.
- Relativistic signatures influence the breakdown velocity.
- Universal ME conductivity determines the instability threshold.

## Abstract

One of the intrinsic drift velocity limit of the quantum Hall effect is the collective magneto-exciton (ME) instability. It has been demonstrated in bilayer graphene (BLG) using noise measurements. We reproduce this experiment in monolayer graphene (MLG), and show that the same mechanism carries a direct relativistic signature on the breakdown velocity. Based on theoretical calculations of MLG- and BLG-ME spectra, we show that Doppler-induced instabilities manifest for a ME phase velocity determined by a universal value of the ME conductivity, set by the Hall conductance.