Magnetoexcitons and optical absorption of bilayer-structured topological insulators

TL;DR

This paper theoretically investigates the optical absorption of magnetoexcitons in topological insulator bilayers under strong magnetic fields, providing analytical formulas and insights into experimental detection.

Contribution

It introduces a general analytical formula for optical absorption selection rules in topological insulator bilayers, including Coulomb interactions, aiding interpretation of experimental spectra.

Findings

Derived a general analytical formula for absorption selection rules.

Explained the formation of Dirac-type magnetoexcitons.

Discussed complex absorption spectra with inter-Landau-level Coulomb interactions.

Abstract

Optical absorption properties of magnetoexcitons in topological insulator bilayers under a strong magnetic field are theoretically studied. A general analytical formula of optical absorption selection rule is obtained in the noninteracting as well as Coulomb intra-Landau-level interacting cases, which remarkably helps to interpret the resonant peaks in absorption spectroscopy and the corresponding formation of Dirac-type magnetoexcitons. We also discuss the optical absorption spectroscopy of magnetoexcitons in the presence of inter-Landau-level Coulomb interaction, which becomes more complex. Our results could be detected in the magneto-optical experiments.