Observation of cyclotron antiresonance in the topological insulator Bi2Te3

TL;DR

This paper reports the experimental discovery of cyclotron antiresonance in Bi2Te3, a topological insulator, revealing unconventional magnetic responses possibly due to an imaginary cyclotron resonance frequency.

Contribution

It presents the first observation of cyclotron antiresonance in a 3D topological insulator and introduces a novel theoretical idea of an imaginary cyclotron resonance frequency.

Findings

Inverted spectral feature in magneto-reflectance response.

Evidence of unconventional Lorentz force behavior.

Proposal of imaginary cyclotron resonance frequency.

Abstract

We report on the experimental observation of a cyclotron antiresonance in a canonical 3D topological insulator Bi$_2$Te$_3$. Magneto-reflectance response of single crystal Bi$_2$Te$_3$ was studied in 18 Tesla magnetic field, and compared to other topological insulators studied before, the main spectral feature is inverted. We refer to it as an antiresonance. In order to describe this unconventional behavior we propose the idea of an imaginary cyclotron resonance frequency, which on the other hand indicates that the form of the Lorentz force that magnetic field exerts on charge carriers takes an unconventional form.