Resonance-enhanced inelastic He-atom scattering from subsurface optical phonons of Bi(111)

Kraus, Patrick; Tamtögl, Anton; Mayrhofer-Reinhartshuber, Michael; Benedek, G.; Ernst, Wolfgang

doi:10.1103/physrevb.87.245433

Cited by 20 publications

(20 citation statements)

References 30 publications

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“…Finally, inelastic processes and phonon mediated SARs have been identified in experiments and proven to play important roles [20,18], also for similar systems as in our study, e.g. for helium scattering of the Bi(111) surface [27]. However, from a theoretical point of view, these effects have been mainly considered in the limit of low corrugated surfaces [49,50,51,52].…”

Section: Comparison With Elastic Close-coupled Calcula-supporting

confidence: 72%

A Helium-Surface Interaction Potential of Bi2Te3(111) from Ultrahigh-Resolution Spin-Echo Measurements

et al. 2018

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We have determined an atom-surface interaction potential for the He-Bi 2 Te 3 (111) system by analysing ultrahigh resolution measurements of selective adsorption resonances. The experimental measurements were obtained using 3 He spin-echo spectrometry. Following an initial free-particle model analysis, we use elastic close-coupling calculations to obtain a three-dimensional potential. The three-dimensional potential is then further refined based on the experimental data set, giving rise to an optimised potential which fully reproduces the experimental data. Based on this analysis, the He-Bi 2 Te 3 (111) interaction potential can be described by a corrugated Morse potential with a well depth D = (6.22 ± 0.05) meV, a stiffness κ = (0.92 ± 0.01)Å −1 and a surface electronic corrugation of (9.6 ± 0.2)% of the lattice constant. The improved uncertainties of the atom-surface interaction potential should also enable the use in inelastic closecoupled calculations in order to eventually study the temperature dependence and the line width of selective adsorption resonances.

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Section: Comparison With Elastic Close-coupled Calcula-supporting

confidence: 72%

A Helium-Surface Interaction Potential of Bi2Te3(111) from Ultrahigh-Resolution Spin-Echo Measurements

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: 71%

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

Tamtögl

Kraus

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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“…The modulation amplitude for the surface state was too small for quantitative discussion, however. Inelastic helium atom scattering measurements also successfully observed surface and subsurface phonons of Bi(111) [13,17]. The experimentally obtained phonon-dispersion relation clearly exhibited a few low-frequency phonon modes, which were attributed to the acoustic phonons from the first and second topmost bilayers.…”

Section: Introductionmentioning

confidence: 77%

Ultrafast phonon dynamics of epitaxial atomic layers of Bi on Si(111)

et al. 2015

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Ultrathin bismuth (Bi) layers on Si(111)-7 × 7 undergo a structural phase transformation with reducing the number of atomic layers at 3 bilayers (BL). We investigate the phonon dynamics of the Bi films close to the phase transformation by pump-probe reflectivity measurements. Coherent A 1g and E g phonons at 3 and 2 THz are clearly observed for the Bi layers with thicknesses down to 3 BL, confirming their rhombohedral crystalline structure. The A 1g frequency exhibits an abrupt redshift and splits into two components at 3 BL, which are attributed to the vertical motions of Bi atoms localized at the surface and subsurface bilayers. The E g frequency, by contrast, shows a gradual blueshift with reducing the thickness, possibly due to the lateral compressive stress at the Bi/Si interface. Below 3 BL, no coherent phonon signal is detected, in agreement with the phase transformation to the black-phosphoruslike structure. Our observations indicate that the vertical vibrations are significantly softened at 3 BL, but become almost as hard as those in the bulk crystal by adding another bilayer.

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Resonance-enhanced inelastic He-atom scattering from subsurface optical phonons of Bi(111)

Cited by 20 publications

References 30 publications

A Helium-Surface Interaction Potential of Bi2Te3(111) from Ultrahigh-Resolution Spin-Echo Measurements

A Helium-Surface Interaction Potential of Bi2Te3(111) from Ultrahigh-Resolution Spin-Echo Measurements

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

Ultrafast phonon dynamics of epitaxial atomic layers of Bi on Si(111)

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