A5039713048- Surface and Thin Film Phenomena
- Magnetic properties of thin films
- Advanced Chemical Physics Studies
- nanoparticles nucleation surface interactions
- Quantum and electron transport phenomena
- Surface Chemistry and Catalysis
- Magnetism in coordination complexes
- Molecular Junctions and Nanostructures
- Theoretical and Computational Physics
- Graphene research and applications
- Force Microscopy Techniques and Applications
- Advanced Materials Characterization Techniques
- Catalytic Processes in Materials Science
- Lanthanide and Transition Metal Complexes
- Advanced NMR Techniques and Applications
- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Electron and X-Ray Spectroscopy Techniques
- Atomic and Subatomic Physics Research
- Electronic and Structural Properties of Oxides
- ZnO doping and properties
- Chemical and Physical Properties of Materials
- Block Copolymer Self-Assembly
- Topological Materials and Phenomena
École Polytechnique Fédérale de Lausanne
2016-2025
IBM Research - Almaden
2008-2025
Karlsruhe Institute of Technology
2010-2025
ORCID
2021
Charles Humbert 8
2018-2019
Institute for Advanced Study
2017
National Institute of Standards and Technology
2014
École Normale Supérieure - PSL
2011
Max Planck Institute for Solid State Research
2002-2010
Technical University of Munich
2008-2010
High-resolution scanning tunneling microscopy data on the reconstructed Au(111) surface are presented that give a comprehensive picture of atomic structure, long-range ordering, and interaction between reconstruction defects in surface. On basis atomically resolved stacking-fault-domain model involving periodic transitions from fcc to hcp stacking top-layer atoms is confirmed. The practically uniform contraction layer along [11\ifmmode\bar\else\textasciimacron\fi{}0] indicates previously...
The isotropic magnetic moment of a free atom is shown to develop giant anisotropy energy due symmetry reduction at an atomically ordered surface. Single cobalt atoms deposited onto platinum (111) are found have 9 millielectron volts per arising from the combination unquenched orbital moments (1.1 Bohr magnetons) and strong spin-orbit coupling induced by substrate. By assembling nanoparticles containing up 40 atoms, further be dependent on single-atom coordination changes. These results...
Designing systems with large magnetic anisotropy is critical to realize nanoscopic magnets. Thus far, the energy per atom in single-molecule magnets and ferromagnetic films remains typically one two orders of magnitude below theoretical limit imposed by atomic spin-orbit interaction. We realized maximum for a 3d transition metal coordinating single Co O site an MgO(100) surface. Scanning tunneling spectroscopy reveals record-high zero-field splitting 58 millielectron volts as well slow...
We present a systematic study of metal−organic honeycomb lattices assembled from simple ditopic molecular bricks and Co atoms on Ag(111). This approach enables us to fabricate size- shape-controlled open nanomeshes with pore dimensions up 5.7 nm. The networks are thermally robust while extending over μm2 large areas as single domains. They shape resistant in the presence further deposited materials represent templates organize guest species realize rotary systems.
Stable magnets from single atoms An important goal in molecular magnetism is to create a permanent magnet atom. Metal adsorbed on surfaces can develop strong magnetization an applied field (paramagnetism). Donati et al. show that holmium magnesium oxide film grown silver substrate residual for temperatures up 30 K and bistabilty lasts 1500 s at 10 (see the Perspective by Khajetoorians Heinrich). The atom avoids spin relaxation combination of quantum-state symmetry preventing interacting with...
The friction force on a nanometer-sized tip sliding surface is related to the thermally activated hopping of contact atoms an effective atomic interaction potential. A general analytical expression relates height this potential and attempt frequency measurements velocity dependence performed with microscope. While roughly proportional normal load, falls in range mechanical eigenfrequencies probing surface.
The interaction of oxygen with Al(111) was studied by scanning tunneling microscopy (STM). Chemisorbed and surface oxides can be distinguished in STM images, where for moderate tunnel currents independent the bias voltage former are imaged as depressions, while latter appear protrusions. An absolute coverage scale established counting O adatoms. initial sticking coefficient is determined to so=0.005. Upon chemisorption at 300 K adlayer characterized randomly distributed, immobile, individual...
Variable-temperature scanning tunneling microscopy was used to study the effect of kinetic cluster energy and rare-gas buffer layers on deposition process size-selected silver nanoclusters a platinum(111) surface. Clusters with impact energies ≤1 electron volt per atom could be landed nondestructively bare substrate, whereas at higher fragmentation substrate damage were observed. elevated soft-landed via an argon layer platinum which efficiently dissipated energy. Nondestructive represents...
The resolution of individual atoms in scanning-tunneling-microscopy (STM) images Al(111) is demonstrated. From results gap-width and energy-dependent measurements the corrugation observed STM cannot reflect electronic structure Al surface near ${E}_{F}$, as usually assumed for such images, but must be due to tip-surface interactions. On basis an investigation process tip preparation, elastic deformation frontmost end mediated by adhesive interactions proposed predominant factor...
Scanning-tunneling-microscopy observations on an Al(111) surface reveal that O adatoms at 300 K are practically immobile. Low-coverage overlayers formed by dissociative chemisorption of ${\mathrm{O}}_{2}$ consist essentially only single isolated atoms rather than pairs adjacent atoms. Hence, upon dissociation, least part the energy must be transformed into translational parallel to which causes two separate from each other 80 \AA{} before excess is dissipated. The lifetime these ``hot''...
The velocity and humidity dependence of nanoscopic sliding friction has been studied on CrN diamondlike carbon surfaces with an atomic force microscope. surface wettability is found to be decisive. Partially hydrophilic show a logarithmic decrease increasing velocity, the slope which varies drastically humidity, whereas partially hydrophobic we confirm formerly reported increase. A model for thermally activated nucleation water bridges between tip sample asperities fully reproduces experimental data.
The influence of strain on diffusion and nucleation has been studied by means scanning tunneling microscopy effective-medium theory for Ag self-diffusion strained unstrained (111) surfaces. Experimentally, the barrier is observed to be substantially lower a pseudomorphic monolayer Pt(111), 60 meV, compared that Ag(111), 97 meV. calculations show this strong effect due 4.2% compressive Pt. It shown in general isotropic two-dimensional as well its relief via dislocations have drastic surface...
We report on long-range interactions between adsorbates metal surfaces with a surface state. A comparison of three adsorbate/substrate systems [Cu/Cu(111), Co/Cu(111), and Co/Ag(111)] suggests the general existence such shows up common characteristics. In all cases, interaction energy $E(r)$ manifests itself to distance 60 \AA{}, decays as ${1/r}^{2},$ oscillates period ${\ensuremath{\lambda}}_{\mathrm{F}}/2.$ Our data are in excellent agreement theory establish link spatial variation...
The present tunneling microscopy study reveals that the growth of silver on Pt(111) at substrate temperatures above 620 K results in formation a two-dimensional alloy consisting Ag clusters dissolved Pt layer [${\mathit{FTHETA}}_{\mathrm{Ag}}$0.5 monolayer (ML)] and matrix (0.5 ML${\mathit{FTHETA}}_{\mathrm{Ag}}$1 ML), respectively. embedded have narrow size distribution centered around 10 \AA{}. dissolution into surface vice versa proceeds from step edges is confined to topmost layer....
High-density arrays $(5\ifmmode\times\else\texttimes\fi{}{10}^{6} {\mathrm{cm}}^{\ensuremath{-}1})$ of parallel nanowires have been grown using the vicinal Pt(997) surface as a template. Single monatomic rows Ag and Cu can be deposited with subrow precision. We demonstrate real-time monitoring characterization growth atomic chains function temperature by thermal energy helium atom scattering. Scanning tunneling microscopy provides further insight into structure metal rows. Growth mode...
Independent symmetries characterize the evolving network and metal surface on which forms in surface-assisted assembly of ligands centers to 2D honeycomb networks comprising threefold coordination motifs (see picture, Co purple, N green). This type coordination, is rarely encountered 3D metal–organic frameworks, promoted by strict confinement a environment.
We report an experimental and a theoretical study of the radial elasticity multiwalled carbon nanotubes as function external radius. use atomic force microscopy apply small indentation amplitudes in order to stay linear regime. The number layers for given tube radius is inferred from transmission electron microscopy, revealing constant ratios internal radii. This enables comparison with molecular dynamics results, which also shed some light onto applicability Hertz theory this context. Using...
Nucleation and growth of Pd on cleaved MgO(001) surfaces were studied by variable-temperature atomic force microscopy in the temperature range 200--800 K. Constant island densities $(\ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}{10}^{12}{\mathrm{cm}}^{\mathrm{\ensuremath{-}}2})$ observed over a wide range, indicating nucleation kinetics governed point defects with high trapping energy. These results are compared to rate equation model that describes principal atomistic processes,...
We present investigations on noncovalent bonding and supramolecular self-assembly of two related molecular building blocks at a noble metal surface: 4-[trans-2-(pyrid-4-yl-vinyl)]benzoic acid (PVBA) 4-[(pyrid-4-yl-ethynyl)]benzoic (PEBA). These rigid, rodlike molecules comprising the same complementary moieties for hydrogen bond formation are comparable in shape size. For PVBA, ethenylene moiety accounts two-dimensional (2-D) chirality upon confinement to surface; PEBA is linear thus 2-D...