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arXiv · 1704.07416

Electron-Phonon Coupling and Surface Debye Temperature of Bi$_2$Te$_3$(111) from Helium Atom Scattering

Anton Tamtögl·Patrick Kraus·Nadav Avidor·Martin Bremholm·Ellen M. J. Hedegaard·Bo B. Iversen·Marco Bianchi·Philip Hofmann·John Ellis·William Allison·Giorgio Benedek·Wolfgang E. Ernst
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Abstract

We have studied the topological insulator Bi$_2$Te$_3$(111) by means of helium atom scattering. The average electron-phonon coupling $λ$ of Bi$_2$Te$_3$(111) is determined by adapting a recently developed quantum-theoretical derivation of the helium scattering probabilities to the case of degenerate semiconductors. Based on the Debye-Waller attenuation of the elastic diffraction peaks of Bi$_2$Te$_3$(111), measured at surface temperatures between $110~\mbox{K}$ and $355~\mbox{K}$, we find $λ$ to be in the range of $0.04-0.11$. This method allows to extract a correctly averaged $λ$ and to address the discrepancy between previous studies. The relatively modest value of $λ$ is not surprising even though some individual phonons may provide a larger electron-phonon interaction. Furthermore, the surface Debye temperature of Bi$_2$Te$_3$(111) is determined as ${\rm Θ}_D = (81\pm6)~\mbox{K}$. The electronic surface corrugation was analysed based on close-coupling calculations. By using a corrugated Morse potential a peak-to-peak corrugation of 9% of the lattice constant is obtained.

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Anton Tamtögl, Patrick Kraus, Nadav Avidor, Martin Bremholm, Ellen M. J. Hedegaard, Bo B. Iversen, Marco Bianchi, Philip Hofmann, John Ellis, William Allison, Giorgio Benedek, Wolfgang E. Ernst. 2017-04-24. Electron-Phonon Coupling and Surface Debye Temperature of Bi$_2$Te$_3$(111) from Helium Atom Scattering. https://doi.org/10.1103/physrevb.95.195401

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