Stability of the Bi2Se3(111) topological state: electron-phonon and -defect scattering

TL;DR

This study investigates the stability and electron-phonon interactions of the topological surface state in Bi2Se3(111), revealing a significant electron-phonon coupling and vulnerability to surface defects that disrupt the topological state.

Contribution

It provides the first detailed measurement of electron-phonon coupling in Bi2Se3(111) and examines how surface defects affect the topological surface state.

Findings

Electron-phonon coupling constant lambda=0.25(5).

Topological state is sensitive to surface defects and becomes unobservable after ion bombardment.

The topological state remains stable against intrinsic surface irregularities unless defects are introduced.

Abstract

The electron dynamics of the topological surface state on Bi2Se3(111) is investigated by temperature-dependent angle-resolved photoemission. The electron-phonon coupling strength is determined in a spectral region for which only intraband scattering involving the topological surface band is possible. The electron-phonon coupling constant is found to be lambda=0.25(5), more than an order of magnitude higher than the corresponding value for intraband scattering in the noble metal surface states. The stability of the topological state with respect to surface irregularities was also tested by introducing a small concentration of surface defects via ion bombardment. It is found that, in contrast to the bulk states, the topological state can no longer be observed in the photoemission spectra and this cannot merely be attributed to surface defect-induced momentum broadening.