Photon dressed electronic states in topological insulators: Tunneling and conductance

TL;DR

This paper explores how circularly polarized light modifies the electronic states of topological insulators, affecting tunneling and conductance, with potential implications for optoelectronic applications.

Contribution

It introduces the concept of photon-dressed states in topological insulators and analyzes their impact on tunneling and conductance, highlighting differences from graphene and 2DEG.

Findings

Photon coupling opens an energy gap in topological insulators.

A critical energy threshold for perfect tunneling is identified.

Distinct behaviors of electrons as massless or massive particles are demonstrated.

Abstract

The surface bound electronic states of three-dimensional topological insulators, as well as the edge states in two-dimensional topological insulators, are investigated in the presence of a circularly polarized light. The strong coupling between electrons and photons is found t o give rise to an energy gap as well as a unique energy dispersion of the dressed states, different from both graphene and conventional two-dimensional electron gas (2DEG). The effects of electron-photon interaction, barrier height and width on the electron tunneling through a p-n junction and on the ballistic conductance in topological insulators are demonstrated by numerical calculations. A critical energy for an incident electron to tunnel perfectly through a barrier is predicted, where electrons behave as either massless Dirac-like or massive Schrodinger-like particles above or below this threshold value. Additionally, these effects are compared with those in zigzag graphene nanoribbons and a 2DEG. Both the similarities and the differences are demonstrated and explained.