Electron-phonon coupling in topological surface states: The role of polar optical modes

Heid, R.; Sklyadneva, I. Yu.; Chulkov, Evgueni V.

doi:10.1038/s41598-017-01128-1

Cited by 56 publications

(71 citation statements)

References 54 publications

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“…The absence of a Kohn anomaly in our measurements is also in accordance with our DFPT calculations, as shown in Figure 5 d) where we report the phonon frequencies at q N est = 2k F = 0.28Å −1 obtained with a particularly careful sampling of the SBZ as described in the . Similar results have been obtained in a recent work by Heid et al 24 from first principles, who could neither find a large e-ph coupling constant nor the presence of a Kohn anomaly. Hence they suggested that the Kohn anomaly observed in 22 may be connected to a strong e-ph interaction in the doped bulk material rather than a surface state.…”

Section: A Dfpt Dispersion Curves and Comparison With Experimentssupporting

confidence: 91%

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

et al. 2018

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We present a combined experimental and theoretical study of the surface vibrational modes of the topological insulator Bi2Te3. Using high-resolution helium-3 spin-echo spectroscopy we are able to resolve the acoustic phonon modes of Bi2Te3(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.

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Section: A Dfpt Dispersion Curves and Comparison With Experimentssupporting

confidence: 91%

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

et al. 2018

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“…Due to the e-ph interaction, large modulations of the surface charge density are induced, 10 which is also important in observing comparatively large inelastic intensities from surface optical modes. 48 The property is common to other layered structures, as recently shown theoretically 49 and experimentally 50,51 for Bi 2 Te 3 (111) and Bi 2 Se 3 (111). In general the overall agreement of the measurements with the calculations is very good.…”

Section: Dispersion Curvesmentioning

confidence: 60%

Statics and dynamics of multivalley charge density waves in Sb(111)

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Mayrhofer-Reinhartshuber

et al. 2019

npj Quantum Mater.

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Charge density waves (CDWs), periodic modulations of the charge density, are among the most abundant and non-trivial ordered phases in condensed matter. Here we demonstrate the occurrence of multi-valley charge density waves (MV-CDW) on the semimetal Sb(111), a phenomenon previously observed at semiconductor surface inversion layers. The topological nature of the pocket surface states in Sb(111) ensures perfect nesting conditions giving rise to sharp peaks in helium atom scattering (HAS) diffraction spectra. The peculiar temperature dependence permits to distinctly associate the diffraction peaks with surface electron and hole-pocket states due to the non-trivial surface electronic band structure known from recent experimental data and present ab-initio calculations. Inelastic HAS spectra, besides providing the surface phonon dispersion curves in agreement with density functional perturbation theory calculations, reveal two additional dispersion curves of elementary excitations in the gap well below Rayleigh waves. They are attributed to collective excitations of the quasi-commensurate MV-CDWs associated with the surface electron M-pocket states at the Fermi level. These findings suggest that HAS can be regarded as a choice spectroscopy for the investigation of surface electronic excitations in the THz domain, opening up a new window for the search of collective phases at surfaces.

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“…Although Al has a higher plasmonic FOM in this spectral region, its plasmonic properties are strongly dependent on the surface oxidation status. 41 Note that the intrinsic electronphonon coupling in the topological surface state of TIs is strong enough to activate the phonon-assisted intraband processes in the plasmonic response, 20,42 which could slightly reduce the FOM values of these TIs.…”

Section: Plasmonics Of Tis At Optical Frequencies J Yin Et Almentioning

confidence: 99%

Plasmonics of topological insulators at optical frequencies

et al. 2017

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The development of nanoplasmonic devices, such as plasmonic circuits and metamaterial superlenses in the visible to ultraviolet frequency range, is hampered by the lack of low-loss plasmonic media. Recently, strong plasmonic response was reported in a certain class of topological insulators. Here, we present a first-principles density functional theory analysis of the dielectric functions of topologically insulating quaternary (Bi,Sb) 2 (Te,Se) 3 trichalcogenide compounds. Bulk plasmonic properties, dominated by interband transitions, are observed from 2 to 3 eV and extend to higher frequencies. Moreover, trichalcogenide compounds are better plasmonic media than gold and silver at blue and UV wavelengths. By analyzing thin slabs, we also show that these materials exhibit topologically protected surface states, which are capable of supporting propagating plasmon polariton modes over an extremely broad spectral range, from the visible to the mid-infrared and beyond, owing to a combination of interand intra-surface band transitions. NPG Asia Materials (2017) 9, e425; doi:10.1038/am.2017.149; published online 25 August 2017 INTRODUCTIONThe fields of metamaterials and plasmonics have seen an extraordinary evolution in recent years, from the initial theoretical predictions of artificial negative refractive indices and cloaking 1,2 to the experimental realization of photonic metadevices with various functionalities that can be engineered and obtained on demand. 3,4 However, the practical implementations of plasmonic and metamaterial devices have long been hampered by energy dissipation in plasmonic media, especially in the visible to ultraviolet (UV) range, where even the best plasmonic metals (such as gold, silver and aluminum) suffer from strong dissipation due to interband electronic transitions and Drude losses. 5 This has inspired a search for alternative low-loss plasmonic materials for optical devices operating at high frequencies. 6,7 Candidates that are currently being investigated include highly doped semiconductors, metallic alloys, nitrides and oxides 8 and, more recently, twodimensional materials and topological insulator (TI) materials.TIs represent a new quantum phase of matter, which originates from the topological character of the bulk electronic bands in certain materials. The strong spin-orbit coupling in such materials leads to a band inversion and the appearance of Dirac surface states in the band gap. These topological surface states are chiral and protected from back-scattering by time-reversal symmetry. As a consequence, charge carriers from topologically protected surface states can carry current and are free to move parallel to the surface. Thus, TIs are ideal candidates to realize exotic plasmonic phenomena. Localized plasmons have recently been observed in TIs at THz frequencies (in Bi 2 Se 3 ) 9,10 as well as visible-to-UV frequencies (in single crystal

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Electron-phonon coupling in topological surface states: The role of polar optical modes

Cited by 56 publications

References 54 publications

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

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

Statics and dynamics of multivalley charge density waves in Sb(111)

Plasmonics of topological insulators at optical frequencies

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Electron-phonon coupling in topological surface states: The role of polar optical modes

Cited by 56 publications

References 54 publications

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

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

Statics and dynamics of multivalley charge density waves in Sb(111)

Plasmonics of topological insulators at optical frequencies

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Product

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

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