Details

Autor(en) / Beteiligte

• Tamtögl, Anton
• Campi, Davide
• Bremholm, Martin
• Hedegaard, Ellen M. J
• Iversen, Bo B
• Bianchi, Marco
• Hofmann, Philip
• Marzari, Nicola
• Benedek, Giorgio
• Ellis, John
• Allison, William

Titel

Nanoscale surface dynamics of Bi2Te3(111): observation of a prominent surface acoustic wave and the role of van der Waals interactions

Ist Teil von

• Nanoscale, 2018-08, Vol.1 (3), p.14627-14636

Ort / Verlag

Cambridge: Royal Society of Chemistry

Erscheinungsjahr

2018

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• We present a combined experimental and theoretical study of the surface vibrational modes of the topological insulator Bi 2 Te 3 . Using high-resolution helium-3 spin-echo spectroscopy we are able to resolve the acoustic phonon modes of Bi 2 Te 3 (111). The low energy region of the lattice vibrations is mainly dominated by the Rayleigh mode which has been claimed to be absent in previous experimental studies. The appearance of the Rayleigh mode is consistent with previous bulk lattice dynamics studies as well as theoretical predictions of the surface phonon modes. Density functional perturbation theory calculations including van der Waals corrections are in excellent agreement with the experimental data. Comparison of the experimental results with theoretically obtained values for films with a thickness of several layers further demonstrate, that for an accurate theoretical description of three-dimensional topological insulators with their layered structure the inclusion of van der Waals corrections is essential. The presence of a prominent surface acoustic wave and the contribution of van der Waals bonding to the lattice dynamics may hold important implications for the thermoelectric properties of thin-film and nanoscale devices. A prominent surface acoustic wave dominates the vibrational dynamics of Bi 2 Te 3 (111). Theoretical calculations reveal the crucial role of vdW interactions.