Optical transitions in two-dimensional topological insulators with point defects

TL;DR

This paper investigates how point defects in two-dimensional topological insulators influence optical absorption spectra, revealing characteristic peaks due to bound states that reflect the topological nature of the material.

Contribution

It demonstrates the specific optical features caused by defect-induced bound states in 2D topological insulators, highlighting their unique spectral signatures.

Findings

Defects produce distinct absorption peaks in spectra.

Bound states exhibit intracenter transitions between electron-like and hole-like states.

Optical features are inherent to the topological properties of the insulators.

Abstract

Nontrivial properties of electronic states in topological insulators are inherent not only to the surface and boundary states, but to bound states localized at structure defects as well. We clarify how the unusual properties of the defect-induced bound states are manifested in optical absorption spectra in two-dimensional topological insulators. The calculations are carried out for defects with short-range potential. We find that the defects give rise to the appearance of specific features in the absorption spectrum, which are an inherent property of topological insulators. They have the form of two or three absorption peaks that are due to intracenter transitions between electron-like and hole-like bound states.