Inelastic helium atom scattering from Sb2Te3(111): phonon dispersion, focusing effects and surfing. Issue 13 (2nd November 2020)

• Record Type: Journal Article
• Authors: Ruckhofer, Adrian; Halbritter, Simon; Lund, Henriette E.; Holt, Ann Julie U.; Bianchi, Marco; Bremholm, Martin; Benedek, Giorgio; Hofmann, Philip; Ernst, Wolfgang E.; Tamtögl, Anton
• Is Part Of: Physical chemistry chemical physics. Volume 23:Issue 13(2021)
• Page Start: 7806
• Page End: 7813
• Publication Date: 2020-11-02
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d0cp04738d
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : We report the surface phonon dispersion of the topological insulator Sb2 Te3 together with a number of additional inelastic events, including resonance enhancement, kinematical focusing and surfing. Abstract : We present an experimental study of inelastic scattering processes on the (111) surface of the topological insulator Sb2 Te3 using helium atom scattering. In contrast to other binary topological insulators such as Bi2 Se3 and Bi2 Te3, Sb2 Te3 is much less studied and the as-grown Sb2 Te3 sample turns out to be p-doped, with the Fermi-level located below the Dirac-point as confirmed by angle-resolved photoemission spectroscopy. We report the surface phonon dispersion along both high symmetry directions in the energy region below 11 meV, where the Rayleigh mode exhibits the strongest intensity. The experimental data is compared with a study based on density functional perturbation theory calculations, providing good agreement except for a set of additional peculiar inelastic events below the Rayleigh mode. In addition, an analysis of angular scans with respect to a number of additional inelastic events is presented, including resonance enhancement, kinematical focusing, focused inelastic resonance and surfing. In the latter case, phonon-assisted adsorption of the incident helium atom gives rise to a bound state where the helium atom rides the created Rayleigh wave.