Collective modes and the far-infrared absorption of the two-dimensional electron gas in a periodic quantizing magnetic field

TL;DR

This paper studies how a periodically modulated magnetic field affects the collective excitations and far-infrared absorption spectra of a two-dimensional electron gas, revealing complex spectral features linked to electronic band structure.

Contribution

It introduces a self-consistent Hartree approximation analysis of FIR absorption in a 2D electron gas under magnetic modulation, highlighting the impact of magnetic patterns on spectral features.

Findings

Absorption spectra are directly related to electronic energy bands.

Magnetic modulation results in richer absorption spectral structures.

The static electron density response differs significantly from electric modulation.

Abstract

We investigate the far-infrared (FIR) absorption of a two-dimensional electron gas in a periodically modulated quantizing magnetic field. The magnetic field varies along only one spatial direction and the external time-dependent electric field is linearly polarized along that axis. The mutual Coulomb interaction of the electrons is treated self-consistently in the ground state and in the absorption calculation within the Hartree approximation. The effects of the magnetic material on top of the heterostructure as a grating coupler is included in the time-dependent incident FIR electric field. We show that similar to an electric modulation, the absorption can be directly correlated to the underlying electronic energy bands. In addition, the magnetic modulation leads to absorption spectra with a richer structure due to the quite different static response of the electron density to the modulation.