Tunneling Spectroscopy of Disordered Two-Dimensional Electron Gas in the Quantum Hall Regime

TL;DR

This paper investigates the tunneling density of states in a disordered two-dimensional electron gas within the quantum Hall regime, highlighting the effects of Coulomb interactions and disorder on the spectral features.

Contribution

It provides a quantitative explanation of the tunneling spectrum features using a Hartree-Fock model, emphasizing the role of Coulomb interactions and magnetic field effects.

Findings

High energy spectral features depend on filling factor and temperature.

Coulomb interactions with localized states influence the tunneling spectrum.

Magnetic field quenches kinetic energy, shaping the addition spectrum.

Abstract

Recently, Dial et al. presented measurements of the tunneling density of states into the bulk of a two dimensional electron gas under strong magnetic fields. Several high energy features appear in the measured spectrum showing a distinct dependence on filling factor and a unique response to temperature. We present a quantitative account of the observed structure, and argue it results from the repulsive Coulomb interactions between the tunneling electron and states localized at disorder potential wells. The quenching of the kinetic energy by the applied magnetic field leads to an electron addition spectrum that is primarily determined by the external magnetic field and is nearly independent of the disorder potential. Using a Hartree-Fock model we reproduce the salient features of the observed structure.