Tunable Dirac Fermion Dynamics in Topological Insulators

TL;DR

This study uses high-resolution photoemission to analyze Dirac fermion dynamics in topological insulators, revealing electron-phonon coupling and dominant electron-disorder interactions, with tunable properties via composition and charge control.

Contribution

It provides detailed insights into the electron interactions in topological insulators and demonstrates how their Dirac fermion dynamics can be tuned through composition and charge manipulation.

Findings

Electron-phonon coupling signatures identified

Electron-disorder interaction dominates scattering

Dirac fermion dynamics can be tuned by composition and charge

Abstract

Three-dimensional topological insulators are characterized by insulating bulk state and metallic surface state involving Dirac fermions that behave as massless relativistic particles. These Dirac fermions are responsible for achieving a number of novel and exotic quantum phenomena in the topological insulators and for their potential applications in spintronics and quantum computations. It is thus essential to understand the electron dynamics of the Dirac fermions, i.e., how they interact with other electrons, phonons and disorders. Here we report super-high resolution angle-resolved photoemission studies on the Dirac fermion dynamics in the prototypical Bi2(Te,Se)3 topological insulators. We have directly revealed signatures of the electron-phonon coupling in these topological insulators and found that the electron-disorder interaction is the dominant factor in the scattering process. The Dirac fermion dynamics in Bi2(Te3-xSex) topological insulators can be tuned by varying the composition, x, or by controlling the charge carriers. Our findings provide crucial information in understanding the electron dynamics of the Dirac fermions in topological insulators and in engineering their surface state for fundamental studies and potential applications.