Butterfly-like spectra and collective modes of antidot superlattices in magnetic fields

TL;DR

This paper studies the energy spectra and collective modes of electrons in antidot superlattices under magnetic fields, revealing self-similar butterfly patterns and the effects of screening on bandwidths, with implications for FIR response.

Contribution

It introduces calculations of energy band structures in antidot superlattices considering electron interactions and magnetic fields, highlighting self-similarity and screening effects on the spectra.

Findings

Energy spectra show Hofstadter butterfly-like self-similarity.

Screening causes oscillations in bandwidths with magnetic field.

FIR absorption peaks include semiclassical and interband transition features.

Abstract

We calculate the energy band structure for electrons in an external periodic potential combined with a perpendicular magnetic field. Electron-electron interactions are included within a Hartree approximation. The calculated energy spectra display a considerable degree of self-similarity, just as the ``Hofstadter butterfly.'' However, screening affects the butterfly, most importantly the bandwidths oscillate with magnetic field in a characteristic way. We also investigate the dynamic response of the electron system in the far-infrared (FIR) regime. Some of the peaks in the FIR absorption spectra can be interpreted mainly in semiclassical terms, while others originate from inter(sub)band transitions.