Fermi-edge transmission resonance in graphene driven by a single Coulomb impurity

TL;DR

This paper reports the first observation of Fermi edge singularity in graphene caused by Coulomb impurities, revealing strong many-body effects and enabling defect spectroscopy in quantum Hall regimes.

Contribution

It demonstrates the first experimental detection of FES in Dirac fermions in graphene driven by isolated Coulomb impurities, and introduces a new defect-spectroscopy method.

Findings

FES manifests as abrupt conductance changes of about e^2/h.

Total many-body screening of Coulomb impurities observed.

Graphene's sensitivity used for defect spectroscopy in quantum Hall regime.

Abstract

The interaction between the Fermi sea of conduction electrons and a non-adiabatic attractive impurity potential can lead to a power-law divergence in the tunneling probability of charge through the impurity. The resulting effect, known as the Fermi edge singularity (FES), constitutes one of the most fundamental many-body phenomena in quantum solid state physics. Here we report the first observation of FES for Dirac Fermions in graphene driven by isolated Coulomb impurities in the conduction channel. In high-mobility graphene devices on hexagonal boron nitride substrates, the FES manifests in abrupt changes in conductance with a large magnitude $\approx e^{2}/h$ at resonance, indicating total many-body screening of a local Coulomb impurity with fluctuating charge occupancy. Furthermore, we exploit the extreme sensitivity of graphene to individual Coulomb impurities, and demonstrate a new defect-spectroscopy tool to investigate strongly correlated phases in graphene in the quantum Hall regime.