Electron-hole coexistence in disordered graphene probed by high-field magneto-transport

TL;DR

This study investigates disordered graphene under high magnetic fields, revealing coexistence of electrons and holes near the charge neutrality point, with implications for understanding quantum Hall effects and puddle formation.

Contribution

It provides experimental evidence of electron-hole puddle coexistence in disordered graphene at high magnetic fields, linking resistance fluctuations to puddle size.

Findings

Integer Quantum Hall Effect observed at high doping levels

Vanishing Hall resistance near charge neutrality point

Resistance fluctuations correlated with puddle size

Abstract

We report on magneto-transport measurement in disordered graphene under pulsed magnetic field of up to 57T. For large electron or hole doping, the system displays the expected anomalous Integer Quantum Hall Effect (IQHE) specific to graphene up to filling factor $\nu=2$. In the close vicinity of the charge neutrality point, the system breaks up into co-existing puddles of holes and electrons, leading to a vanishing Hall and finite longitudinal resistance with no hint of divergence at very high magnetic field. Large resistance fluctuations are observed near the Dirac point. They are interpreted as the the natural consequence of the presence of electron and hole puddles. The magnetic field at which the amplitude of the fluctuations are the largest is directly linked to the mean size of the puddles.