Exotic Surfaces
Exotic Surfaces
Disciplines
Chemistry (20%); Physics, Astronomy (80%)
Keywords
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Topological Insulator,
Atom scattering from surfaces,
Semimetal,
Surface phonon dispersion,
Atom surface interaction,
Electron-phonon interaction
The present application seeks to understand the properties of novel and unusual surfaces, for which few dynamical measurements exist. The applicant plans to spend a research period of 24 months at the University of Cambridge in the Surface Physics Group under the supervision of Dr. William Allison. The research group of Dr. William Allison is the world`s only group that operates a helium-3 spin-echo spectrometer which can resolve energy changes as small as 20 neV. Spin-echo measurements on the semimetal Bi(111) and the topological insulator PbBi 2 Te4 (111) will provide new benchmark data that will assist in the development of theoretical approaches to understand the fundamental atom-surface interaction on semimetal and topological insulator surfaces. In particular the spin-echo technique is the only method that can provide data with sufficient experimental resolution for direct measurements of the mode-selected electron-phonon interaction. Furthermore, the possible investigation of acoustic surface plasmons in a spectral region inaccessible to any other technique, is an extremely attractive aspect not yet explored. Based on the analysis of the spin-echo measurements a theoretical concept for the He-Bi(111) interaction will be developed which may also be adapted for other semimetals. In an additional return phase of 12 months at the Institute of Experimental Physics (Graz University of Technology) the knowledge obtained in the group in Cambridge and the first application of this concept for the He-Bi(111) system will be further developed. This includes the interpretation of the He-PbBi 2 Te4 (111) data measured in Cambridge. The data will be used to find an appropriate atom-surface interaction model for topological insulator surfaces. Finally the influence of adsorbed atomic hydrogen onto the Bi(111) surface with the heading phrase "the lightest on the heaviest" will be investigated experimentally. While an understanding of the model semimetal bismuth is of great interest for topological insulators and spintronics, topological insulators themselves are promising candidates for potential applications ranging from spintronics to quantum computation. Despite their great importance, especially in the case of topological insulators, semimetals have never been approached with helium atom scattering due to their intrinsic complexity of being surface conductors (even superconductors) and strongly corrugated at the same time. The applicant`s expertise in helium scattering on these surface systems combined with the world-leading experimental facilities available in Cambridge will generate new understanding at a fundamental level to these promising materials. Ongoing cooperation with the University of Cambridge will provide continuous exchange of knowledge and the realization of joint experiments.
The aim of this project was to understand the properties of novel and unusual surfaces, so- called semimetals and topological insulators, for which few dynamical measurements exist. Therefore the fellow spent a research period of 24 months at the University of Cambridge in order to run helium spin-echo measurements on the described surfaces followed by a return phase of 12 months at Graz University of Technology. Among the most important results are the development of a novel approach to measure the electron-phonon coupling of topological insulators and the first experimental observation of the atomic-scale motion of water molecules on the semimetal graphene. Both results are fundamentally new and are expected to gain interest by a broad community. A short description of these results is given below, a summary of all results obtained during the course of the project can be found in the detailed report. One of the major objectives for technical applications of topological insulators is surface dominated electron transport. However, the motion of electrons in a solid can be perturbed due to scattering by vibrations (phonons). Phonons are always present for a material at room temperature. The impact of these phonons on the electrons is described by a parameter, the so-called electron-phonon coupling . Depending on the material, the magnitude of the electron-phonon coupling can vary greatly. The fellow was able to develop a novel approach which allows to determine the electron-phonon coupling from experimental measurements. First results for the topological insulator Bi2 Te3 show that the electron-phonon coupling is rather weak for this material. With respect to potential applications it suggests that Bi2Te3 may be a particularly useful material for fast electronic devices. Furthermore, the fellow was able to study the atomic-scale motion (diffusion) of water molecules on the semimetal graphene. On a microscopic scale the molecule moves/hops along the surface whereupon the energy necessary for this motion is provided due to the thermal energy (temperature) of the sur- face. In contrast to the movement of water molecules on metal surfaces, its motion on the semimetal graphene is strongly influenced by interactions between the individual molecules. One reason for this might be the hydrophobic nature of the graphene surface. The measurements show that under certain conditions the water molecules tend to avoid each other, i.e. there is a repulsive interaction between the individual water molecules. This effect occurs due to the electric dipole of a water molecule. Loosely speaking, in analogy to a magnetic moment, one may imagine each water molecule being a little magnet: If these magnets are aligned the same way they will repel each other.
- University of Cambridge - 100%
Research Output
- 284 Citations
- 34 Publications
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2018
Title Polarisation in spin-echo experiments: Multi-point and lock-in measurements DOI 10.1063/1.5017276 Type Journal Article Author Tamtögl A Journal Review of Scientific Instruments Pages 023902 Link Publication -
2018
Title A Helium-Surface Interaction Potential of Bi2Te3(111) from Ultrahigh-Resolution Spin-Echo Measurements DOI 10.1016/j.susc.2018.02.006 Type Journal Article Author Tamtögl A Journal Surface Science Pages 25-31 Link Publication -
2018
Title Nanoscale surface dynamics of Bi 2 Te 3 (111): observation of a prominent surface acoustic wave and the role of van der Waals interactions DOI 10.1039/c8nr03102a Type Journal Article Author Tamtögl A Journal Nanoscale Pages 14627-14636 Link Publication -
2019
Title Helium–Surface Interaction and Electronic Corrugation of Bi2Se3(111) DOI 10.1021/acs.jpcc.9b03450 Type Journal Article Author Ruckhofer A Journal The Journal of Physical Chemistry C Pages 17829-17841 Link Publication -
2016
Title Note: A simple sample transfer alignment for ultra-high vacuum systems DOI 10.1063/1.4954728 Type Journal Article Author Tamtögl A Journal Review of Scientific Instruments Pages 066108 Link Publication -
2016
Title Continuous Compressed Sensing for Surface Dynamical Processes with Helium Atom Scattering DOI 10.1038/srep27776 Type Journal Article Author Jones A Journal Scientific Reports Pages 27776 Link Publication -
2015
Title Graphene on Ni(111): Electronic Corrugation and Dynamics from Helium Atom Scattering DOI 10.1021/acs.jpcc.5b08284 Type Journal Article Author Tamto¨Gl A Journal The Journal of Physical Chemistry C Pages 25983-25990 Link Publication -
2016
Title Ballistic Diffusion in Polyaromatic Hydrocarbons on Graphite DOI 10.1021/acs.jpclett.6b02305 Type Journal Article Author Calvo-Almaza´N I Journal The Journal of Physical Chemistry Letters Pages 5285-5290 Link Publication -
2017
Title Electron-phonon coupling and surface Debye temperature of Bi2Te3(111) from helium atom scattering DOI 10.1103/physrevb.95.195401 Type Journal Article Author Tamtögl A Journal Physical Review B Pages 195401 Link Publication -
2018
Title Ultrafast molecular transport on carbon surfaces: The diffusion of ammonia on graphite DOI 10.1016/j.carbon.2017.09.104 Type Journal Article Author Tamtögl A Journal Carbon Pages 23-30 Link Publication -
2021
Title Motion of water monomers reveals a kinetic barrier to ice nucleation on graphene DOI 10.1038/s41467-021-23226-5 Type Journal Article Author Tamtögl A Journal Nature Communications Pages 3120 Link Publication -
2021
Title Inter-adsorbate forces and coherent scattering in helium spin-echo experiments DOI 10.1039/d0cp04539j Type Journal Article Author Ward D Journal Physical Chemistry Chemical Physics Pages 7799-7805 Link Publication -
2020
Title Measuring the Electron–Phonon Interaction in Two-Dimensional Superconductors with He-Atom Scattering DOI 10.3390/condmat5040079 Type Journal Article Author Benedek G Journal Condensed Matter Pages 79 Link Publication -
2023
Title Observation of Dirac Charge-Density Waves in Bi2Te2Se DOI 10.3390/nano13030476 Type Journal Article Author Ruckhofer A Journal Nanomaterials Pages 476 Link Publication -
2017
Title Structure and dynamics investigations of a partially hydrogenated graphene/Ni(111) surface DOI http://dx.doi.org/10.1016/j.carbon.2016.12.055 Type Journal Article Author Bahn E Journal Carbon -
2016
Title Adhesion properties of hydrogen on Sb(111) probed by helium atom scattering DOI 10.1209/0295-5075/114/56001 Type Journal Article Author Kraus P Journal Europhysics Letters Pages 56001 Link Publication -
2017
Title Structure and dynamics investigations of a partially hydrogenated graphene/Ni(111) surface DOI 10.1016/j.carbon.2016.12.055 Type Journal Article Author Bahn E Journal Carbon Pages 504-510 -
2015
Title Surface Structure of Bi(111) from Helium Atom Scattering Measurements. Inelastic Close-Coupling Formalism DOI 10.1021/acs.jpcc.5b05010 Type Journal Article Author Kraus P Journal The Journal of Physical Chemistry C Pages 17235-17242 Link Publication -
2015
Title Continuous Compressed Sensing of Inelastic and Quasielastic Helium Atom Scattering Spectra DOI 10.48550/arxiv.1510.00555 Type Preprint Author Jones A -
2017
Title Electron-Phonon Coupling and Surface Debye Temperature of Bi$_2$Te$_3$(111) from Helium Atom Scattering DOI 10.48550/arxiv.1704.07416 Type Other Author Kraus P -
2017
Title Adhesion Properties of Hydrogen on Sb(111) Probed by Helium Atom Scattering DOI 10.48550/arxiv.1705.08704 Type Other Author Gösweiner C -
2017
Title Ultrafast Molecular Transport on Carbon Surfaces: The Diffusion of Ammonia on Graphite DOI 10.48550/arxiv.1710.00740 Type Other Author Sacchi M -
2018
Title Polarisation in Spin-Echo Experiments: Multi-point and Lock-in Measurements DOI 10.48550/arxiv.1801.08168 Type Other Author Davey B -
2018
Title Motion of water monomers reveals a kinetic barrier to ice nucleation on graphene DOI 10.48550/arxiv.1810.00650 Type Other Author Bahn E -
2020
Title Inter-adsorbate forces and coherent scattering in helium spin-echo experiments DOI 10.48550/arxiv.2010.02134 Type Other Author Raghavan A -
2021
Title Observation of Dirac Charge Density Waves in Bi$_2$Te$_2$Se DOI 10.48550/arxiv.2111.02323 Type Other Author Benedek G -
2022
Title Structure and dynamics investigations of a partially hydrogenated graphene/Ni(111) surface DOI 10.48550/arxiv.2212.07159 Type Other Author Bahn E -
2021
Title Inter-adsorbate forces and coherent scattering in helium spin-echo experiments. DOI 10.17863/cam.58300 Type Journal Article Author Raghavan A -
2021
Title Motion of water monomers reveals a kinetic barrier to ice nucleation on graphene DOI 10.17863/cam.70412 Type Other Author Bahn E -
2021
Title Motion of water monomers reveals a kinetic barrier to ice nucleation on graphene. DOI 10.17863/cam.71060 Type Journal Article Author Bahn E -
2021
Title Motion of water monomers reveals a kinetic barrier to ice nucleation on graphene. DOI 10.17863/cam.71928 Type Other Author Bahn E -
2021
Title Motion of water monomers reveals a kinetic barrier to ice nucleation on graphene DOI 10.17863/cam.78361 Type Other Author Bahn E -
2020
Title Nanoscopic diffusion of water on a topological insulator DOI 10.1038/s41467-019-14064-7 Type Journal Article Author Tamtögl A Journal Nature Communications Pages 278 Link Publication -
2020
Title Origin of the Electron–Phonon Interaction of Topological Semimetal Surfaces Measured with Helium Atom Scattering DOI 10.1021/acs.jpclett.9b03829 Type Journal Article Author Benedek G Journal The Journal of Physical Chemistry Letters Pages 1927-1933 Link Publication