Papers by Giorgio Benedek
Surface Dynamics of the Wetting Layers and Ultrathin Films on a Dynamic Substrate: (0.5–4) ML Pb/Cu(111)
The Journal of Physical Chemistry C, 2016
The growth of Pb ultrathin films on Cu(111) has been long studied in connection with electronic q... more The growth of Pb ultrathin films on Cu(111) has been long studied in connection with electronic quantum-size effects and for the different temperature-dependent growth kinetics. At low temperature the formation of a wetting layer (1 monolayer (ML)), is followed by an instability of the 2 ML film and a regular layer-by-layer growth is then only observed for more than two monolayers. The 2 ML film was, however, shown to be stabilized by alloying Pb with 20% Tl. This work presents a theoretical study of the dynamics of the wetting layer as well as for 2 ML Pb0.8Tl0.2, 3 and 4 ML Pb on Cu(111) in the 4 × 4 commensurate phase, for which detailed inelastic Helium atom scattering (HAS) spectra have been measured. The present calculations based on the embedded atom method (EAM) include the dynamics of the substrate. Besides leading to a detailed interpretation of the HAS experimental data, the present results are compared with a previous density-functional perturbation theory (DFPT) study for 3 to 7 ML Pb on a ri...
<title>Surface polaritons at nanoporous carbon-silicon interface</title>
ABSTRACT This paper deals with the effect of the electromagnetic field enhancement in three-layer... more ABSTRACT This paper deals with the effect of the electromagnetic field enhancement in three-layered system due to the propagation of a polariton wave at the interface of nanoporous carbon film -- silicon substrate.
The Journal of Physical Chemistry Letters, 2020
Surface lattice dynamics and electron–phonon interaction in cesium ultra-thin films
Physical Chemistry Chemical Physics, 2017
The surface phonon and electron-phonon interactions in the two-dimensional topological insulator ... more The surface phonon and electron-phonon interactions in the two-dimensional topological insulator Bi(111) film are calculated, including the spin-orbit coupling from density-functional perturbation theory. By analyzing the zone-center phonons, an anomalous phonon hardening of two Raman modes, Eg and A1g, in ultrathin films is found and is explained by considering the redistribution of the charge density on the surface of the semimetallic Bi. Surface phonon band structures and the surface phonon density of states are given, and we find that softening and hardening of surface phonon modes occur simultaneously in ultrathin Bi film, but the softening may dominate over the hardening. The calculated electron-phonon coupling constant λ for Bi(111) film is much larger than that for the bulk, which might induce surface-localized superconductivity in this two-dimensional topological insulator.
Surface Dynamics, An Introduction
Springer series in surface sciences, 2018
Surface elastic waves, discovered by Lord Rayleigh in the late 19th century in the realm of seism... more Surface elastic waves, discovered by Lord Rayleigh in the late 19th century in the realm of seismology, besides occurring in nature over a wide range of length scales, have found a broad spectrum of technological applications (Sect. 1.1). Surface acoustic waves (SAWs) on the nanometric scale and their quanta, surface phonons, while allowing for signal processing devices operating in the THz domain, hold information on the structure and the interatomic forces at solid surfaces, which generally differ from those of the solid bulk (Sect. 1.2). Inelastic He atom scattering, as compared to other surface phonon probes, offers convenient kinematical conditions for a high-resolution surface phonon spectroscopy over the complete momentum and energy spectral range (Sect. 1.3).
Experimental Results: Surface Phonons
Springer series in surface sciences, 2018
In this chapter some exemplary high resolution HAS experiments on surface phonon dispersion curve... more In this chapter some exemplary high resolution HAS experiments on surface phonon dispersion curves of single crystal surfaces based largely on the TOF technique are reviewed. A selection is made of significant results for insulator, semiconductor and conducting surfaces, with special attention to the HAS results for metals, semimetals, and layered materials, where evidence is found for important effects of, for example, electron-phonon coupling and the related observation of Kohn anomalies, anomalous longitudinal branches and deep subsurface modes. Studies on complex surfaces with large-period unit cells due to reconstruction or high index orientation are also reviewed. Here also the comparatively high resolution of HAS permits to observe low energy dynamical excitations and their dispersion. Each section is meant as an introduction to the specific phenomena and issues characteristic to each of these different surface types, with special consideration to the questions solved and the new theoretical issues raised. This chapter is complemented by Appendix A, which contains a comprehensive list of the available HAS experimental data on phonon dispersion curves and of the theoretical studies for the different classes of materials, as of early 2018 which update previous reviews: [1, 2] (all systems), [3, 4] (layered compounds), [5, 6] (semiconductors), [7] (metals) and Landot-Bornstein Chapters [8, 9, 10, 484].
Theoretical Methods of Surface Dynamics
Springer series in surface sciences, 2018
The phenomenological models and the quantum theoretical methods which are currently used to calcu... more The phenomenological models and the quantum theoretical methods which are currently used to calculate the dispersion curves of surface phonons are reviewed for the various classes of solids.
Springer series in surface sciences, 2018
Science grows slowly and gently; reaching the truth by a variety of errors. One must prepare the ... more Science grows slowly and gently; reaching the truth by a variety of errors. One must prepare the introduction of a new idea through long and diligent labor; then at a given moment, it emerges as if compelled by a divine necessity.
The Physics of Surface Phonons
Springer series in surface sciences, 2018
The effect of the surface termination on the phonon dispersion curves is illustrated by compariso... more The effect of the surface termination on the phonon dispersion curves is illustrated by comparison with the bulk dispersion curves. After a review of Rayleigh’s theory of surface waves in elastic media the atomistic Born-von Karman theory for bulk phonons is presented. How the surface affects the surface vibrations is illustrated by the Green’s function theory and slab calculations. The chapter closes with some illustrations of surface phonon dispersion curves and their classification.
Springer series in surface sciences, 2018
These experiments are of interest not only because of their confirmation of the predictions of qu... more These experiments are of interest not only because of their confirmation of the predictions of quantum mechanics, but also because they introduce the possibility of applying atom diffraction to investigations of the atomic constitution of surfaces. A beam of atomic hydrogen, for example, … has a range of wavelengths of the right magnitude … centering around 1 Å, and a complete absence of penetration of these waves will ensure that the effects observed arise entirely from the outermost atomic layer.
Physical Review B, 1996
Erratum: Dynamical properties and related optical spectra of fullerenes: The bond-charge-model de... more Erratum: Dynamical properties and related optical spectra of fullerenes: The bond-charge-model description †Phys. Rev. B 50, 6743 "1994… ‡
Nanomaterials
Recently, it was demonstrated that inelastic helium atom scattering from conducting surfaces prov... more Recently, it was demonstrated that inelastic helium atom scattering from conducting surfaces provides a direct measurement of the surface electron–phonon coupling constant (mass enhancement factor λ) via the temperature or the incident wave vector dependence of the Debye–Waller exponent. Here, previous published as well as unpublished helium atom scattering diffraction data from the vicinal surfaces of copper (Cu(11α), with α = 3, 5, 7) and aluminum (Al(221) and Al(332)) were analyzed to determine λ. The results suggested an enhancement with respect to the corresponding data for the low-index surfaces (111) and (001) above the roughening transition temperature. The specific role of steps compared to that of terraces is briefly discussed.
Majorana Fermions in Condensed Matter
MRS Proceedings, 1994
ABSTRACTTopological arguments indicate that an infinite number of covalent carbon crystals may ex... more ABSTRACTTopological arguments indicate that an infinite number of covalent carbon crystals may exist with either diamond-like (sp3), graphitic-like (sp2)- or mixed (sp3/sp2) bonding structure. We investigate the structural, elastic and electronic properties of three prototypical structure: C34, C20 and C22, respectively. All of them form a face-centered cubic lattice. Their properties have been calculated by both Montecarlo and molecular dynamics simulations based on the Tersoff potential. Both the sp3-bonded C34 and the sp2-bonded C20 are found to have a cohesive energy per atom very close to that of diamond. A comparison of elastic and electronic properties to those ones of diamond and graphite are also presented and discussed.
Optical Response Functions of the F Center
Physical Review, 1969
ABSTRACT
Two C28 Clathrates
Carbon Materials: Chemistry and Physics, 2013
ABSTRACT
Libri recevuti e recensioni
Il Nuovo Cimento B, 1984
Journal of Magnetism and Magnetic Materials, 1980
Max-Planck-lnstitut fi~r Festkorperforschung~ 7000 Stuttgart 80, Fed. Rep. Germany Elastic ("Brag... more Max-Planck-lnstitut fi~r Festkorperforschung~ 7000 Stuttgart 80, Fed. Rep. Germany Elastic ("Brags") scattering from antiferromagnetic spin superstructures in EuTe and VJ 2 is observed in Raman scattering in form of new q ffi 0 phonon modes resulting from Brillonin zone foldings. The scattering intensity allows for the determination of the spin-dependent electron-phonon interaction and is a measure of the sublattice magnetization.
1Institute of Experimental Physics, Graz University of Technology, Graz, Austria Donostia Interna... more 1Institute of Experimental Physics, Graz University of Technology, Graz, Austria Donostia International Physics Center (DIPC), Donostia-San Sebastián, Spain 3Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca, Milano, Italy École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland 5Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark [email protected]
The European Physical Journal Special Topics, 2020
A brief illustration is presented about the scientific motivation and contributions of this Speci... more A brief illustration is presented about the scientific motivation and contributions of this Special Issue.
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Papers by Giorgio Benedek