Quenching of quantum Hall effect and the role of undoped planes in multilayered epitaxial graphene

TL;DR

This paper explains the quenching of quantum Hall effects in multilayered epitaxial graphene by proposing a scattering mechanism involving the uncharged layers' Landau levels, which affects electron scattering times.

Contribution

It introduces a novel scattering mechanism involving uncharged graphene layers' Landau levels to explain quantum Hall effect quenching.

Findings

Scattering time depends on magnetic field and can be much shorter than zero-field scattering time.

Coupling between uncharged layers' Landau levels and doped layers explains experimental observations.

High density of states at the Fermi level in uncharged layers influences electron transport.

Abstract

We propose a mechanism for the quenching of the Shubnikov de Haas oscillations and the quantum Hall effect observed in epitaxial graphene. Experimental data show that the scattering time of the conduction electron is magnetic field dependent and of the order of the cyclotron orbit period, \textit{i.e.} can be much smaller than the zero field scattering time. Our scenario involves the extraordinary graphene $n=0$ Landau level of the uncharged layers that produces a high density of states at the Fermi level. We find that the coupling between this $n=0$ Landau level and the conducting states of the doped plane leads to a scattering mechanism having the right magnitude to explain the experimental data.