Unconventional Integer Quantum Hall effect in graphene

TL;DR

This paper explains the unconventional integer quantum Hall effect observed in graphene, which arises from its Dirac-like quasiparticles and quantum anomaly, leading to a unique quantization of Hall conductivity.

Contribution

It reveals the theoretical origin of the unconventional quantum Hall effect in graphene, linking it to the quantum anomaly of the n=0 Landau level.

Findings

Unconventional quantization of Hall conductivity in graphene: $\sigma_{xy} = - (2 e^2/h)(2n+1)$

Experimental confirmation of the unconventional quantum Hall effect in ultrathin graphite films

Connection between Dirac quasiparticles and quantum anomaly in graphene

Abstract

Monolayer graphite films, or graphene, have quasiparticle excitations that can be described by 2+1 dimensional Dirac theory. We demonstrate that this produces an unconventional form of the quantized Hall conductivity $\sigma_{xy} = - (2 e^2/h)(2n+1)$ with $n=0,1,...$, that notably distinguishes graphene from other materials where the integer quantum Hall effect was observed. This unconventional quantization is caused by the quantum anomaly of the $n=0$ Landau level and was discovered in recent experiments on ultrathin graphite films.