The Hofstadter Energy Spectrum for an Interacting 2DEG

TL;DR

This paper investigates how Coulomb interactions influence the Hofstadter butterfly spectrum in a 2D electron gas, revealing preserved gap structures with modified symmetries and conditions for resolving miniband structures.

Contribution

It provides new insights into the interplay between electron interactions and magnetic superlattice spectra, highlighting the preservation and symmetry changes of the Hofstadter gaps.

Findings

Interactions preserve the Hofstadter gap structure

Symmetry depends on Landau band filling

Miniband structure resolvable under certain conditions

Abstract

We study the effects of the Coulomb interactions between electrons on the Hofstadter butterfly, which characterizes the subband structure of the Landau levels of a two-dimensional electron gas in a perpendicular homogeneous magnetic field and a periodic lateral superlattice potential. The interactions essentially preserve the intricate gap structure of the Hofstadter spectra, but with a lower symmetry that depends on the filling of the Landau bands. For short enough periods and strong enough modulation the miniband structure can be resolved in the thermodynamic density of states.