Magneto-Infrared Study of Topological Insulator Bi2Se3

TL;DR

This study uses magneto-infrared spectroscopy to investigate the electronic and phononic properties of thin Bi2Se3 topological insulator flakes under high magnetic fields at low temperature.

Contribution

It provides new insights into electron-phonon interactions and the optical response of Bi2Se3, highlighting differences in Fano resonance behavior compared to previous studies.

Findings

Observation of a Fano resonance at the {} phonon mode

No systematic line broadening of the Fano resonance

Detection of electron-phonon coupling effects

Abstract

We present a magneto-infrared spectroscopic study of thin Bi2Se3 single crystal flakes. Magneto-infrared transmittance and reflectance measurements are performed in the Faraday geometry at 4.2K in a magnetic field up to 17.5T. Thin Bi2Se3 flakes (much less than 1{\mu}m thick) are stabilized on the Scotch tape, and the reduced thickness enables us to obtain appreciable far-infrared transmission through the highly reflective Bi2Se3 single crystals. A pronounced electron-phonon coupling is manifested as a Fano resonance at the {\alpha} optical phonon mode in Bi2Se3, resulting from the quantum interference between the optical phonon mode and the continuum of the electronic states. However, the Fano resonance exhibits no systematic line broadening, in contrast to the earlier observation of a similar Fano resonance in Bi2Se3 using magneto-infrared reflectance spectroscopy.