Publications by Harald Brune | EPFL Graph Search

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The magnetic properties of individual Fe and Co atoms as well as of small Fe clusters adsorbed on two atomic layers of Al2O3 grown on Ni3Al(111) have been investigated by x-ray absorption spectroscopy and x-ray magnetic circular dichroism. We find ratios o ...

Upon annealing above 620 K, submonolayers of Ag deposited on Pt(111) are known to mix into the first surface layer. Thereby the individual Ag atoms reduce the strain fields caused by the lattice mismatch. As observed by scanning tunneling microscopy, careful annealing of the intermixed surface leads to the formation of small round islands with a preferential diameter of 150-300 Angstrom on terraces wider than a critical width of about 400 Angstrom. This indicates that the microscopically intermixed surface

The present paper describes what happens at the surface of a crystal as its temperature steadily increases from zero Kelvin close to the bulk melting temperature. We treat thermal motion, such as the diffusion of individual adatoms establishing mass transp ...

A detailed structural analysis of the surface supported self-assembly of terphenyl-4,4′′-dicarbonitrile molecules (NC−Ph3−CN) linked by Co adatoms on Ag(111) reveals different surface patterns depending on the constraints applied to the system. Without constraints, i.e., sufficient mobility and absence of space limitations at the surface, extended regular honeycomb nanomeshes are formed. On the basis of high-resolution scanning tunneling microscopy images, an atomistic model is derived showing the crystallo

Scanning tunneling microscopy (STM) has been used to investigate the nucleation and stability of iron clusters on the Al2O3/Ni3Al (111) surface as a function of coverage and annealing temperature. We show that atomic beam deposition of iron leads to hexago ...

We report scanning tunneling microscopy observations on the formation of 2D Co-based coordination compounds on the reconstructed Au(111) surface. Preorganized arrays of Co bilayer islands are shown to be local reaction sites, which are consumed in the formation of Co-terephthalate aggregates and regular nanoporous grids. The latter exhibit a planar geometry stabilized by the smooth substrate. The nanogrids are based on a rectangular motif, which is understood as an intrinsic feature of a 2D cobaltous tereph

We report on long-range interactions between adsorbates on 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 of such interactions and shows up common characteristics. In all cases, the interaction energy E(r) manifests itself up to a distance of 60 Angstrom, decays as 1/r(2), and oscillates with a period of lambda(F)/2. Our data are in excellent agreement with theory and establish the link between th

The Hohenberg-Kohn theorem states that the ground state electron density completely determines the external potential acting on an electron system. Inspired by this fundamental theorem, we developed a novel approach to map directly the electron potential in surface systems: linear response theory applied to the total electron density as measured with scanning tunneling microscopy determines the external potential. Potential imaging is demonstrated for the s-p derived surface state on Au(111), where the "her

We have combined magneto-optical Kerr effect, scanning tunneling microscopy, and x-ray magnetic circular dichroism to study the magnetic properties and the morphology of Fe nanoparticles grown on 2 ML thick Al2O3/Ni3Al(111)-(root 67 x root 67)R12.2 degrees with and without Pd seeding. The Ni3Al(111) substrate is ferromagnetic and shows two transition temperatures. The first, T-C1 = 81 +/- 3 K, is attributed to a 20-30 nm thick slightly Ni enriched region; the second, T-C2 = 240 +/- 12 K, is attributed to a

We have used x-ray photoemission electron microscopy (XPEEM) and x-ray absorption spectroscopy (XAS) to characterize MnxGe1-x and CryMnxGe1-x-y films grown by molecular beam epitaxy. The surface layers of the as-grown films probed by XPEEM present segregat ...

Nucleation has been studied on atomic scale for Ag deposition on a Pt(111) surface at low temperature (50-120 K) by means of variable-temperature scanning tunneling microscopy. From island density versus coverage data, the transition from the initial steps of nucleation to growth and coalescence has been studied as a function of temperature. The data show that dimers are stable nuclei for T less-than-or-equal-to 110 K, which facilitates quantitative comparison with rate equations from nucleation theory. The

We demonstrate that electrospray deposition enables the fabrication of highly periodic self-assembled arrays of Fe4H single molecule magnets on graphene/Ir(111). The energetic positions of molecular states are probed by means of scanning tunneling spectros ...

Thin films are often grown away from thermodynamic equilibrium and their morphology becomes determined by kinetics. The final structure of the epitaxial film is decided in the very early stage of submonolayer nucleation and island growth. Recent experiments with scanning tunneling microscopy opened up an unprecedented view of this early stage of epitaxial growth. Variable sample temperatures enabled quantification of the rates of the most important atomic diffusion events and tracing back their interplay yi

We report on the magnetic properties of single Co atoms on graphene on Pt(111). By means of scanning tunneling microscopy spin-excitation spectroscopy, we infer a magnetic anisotropy of K = -8.1 meV with out-of-plane hard axis and a magnetic moment of 2.2 ...

The friction force on a nanometer-sized tip sliding on a surface is related to the thermally activated hopping of the contact atoms on an effective atomic interaction potential. A general analytical expression relates the height of this potential and the hopping attempt frequency to measurements of the velocity dependence of the friction force performed with an atomic force microscope. While the height of the potential is roughly proportional to the normal load, the attempt frequency falls in the range of m

Variable temperature scanning tunneling microscopy at substrate temperatures between 25 and 550 K reveals a transition from diffusion limited aggregation to thermodynamic equilibrium in the two-dimensional (2D) monolayer growth of Ag on the Pt(111) surface. Via deposition temperature control the ''nanostructure'' of the grown 2D-Ag-films can be tuned in a very defined way: from randomly distributed adatoms and small clusters, through highly dendritic islands, dense large islands with irregular or smooth bou

We present optical absorption spectra from the ultraviolet to the visible for size selected neutral Ag-n clusters (n = 5-120) embedded in solid Ne. We compare the spectra to time-dependent density functional calculations (TDDFT) that address the influence ...

Ag(111) surface state electrons have been confined in symmetric and asymmetric Fabry-Perot resonators formed by two atomically parallel step edges. The local density of states in the resonators has been measured by means of low-temperature scanning tunneling spectroscopy and can perfectly be explained with a simple Fabry-Perot-like model. The energy dependent reflection amplitudes and scattering phase shifts of the different kinds of Ag(111) step edges have been determined with high accuracy. The model char

Single lanthanide atoms and molecules are promising candidates for atomic data storage and quantum logic due to the long lifetime of their magnetic quantum states. Accessing and controlling these states through electrical transport requires precise knowled ...

High-pressure scanning tunneling microscopy was used to study the room-temperature adsorption of CO on a Pt(111) single-crystal surface in equilibrium with the gas phase. The coverage was found to vary continuously, and over the entire range from 10(-6)-760 Torr pressure-dependent moire patterns were observed, characteristic of a hexagonal or nearly hexagonal CO overlayer. Two different pressure ranges can be distinguished: below 10(-2) Tort, the moire lattice vector is oriented along a 30degrees high-symme

Harald Brune

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Magnetic anisotropy of Fe and Co adatoms and Fe clusters magnetically decoupled from Ni_{3}Al(111) by an alumina bilayer

Stress relief via island formation of an isotropically strained bimetallic surface layer: The mesoscopic morphology of the Ag/Pt (111) surface alloy

Thermal dynamics at surfaces

Surface-Confined Metal?Organic Nanostructures from Co-Directed Assembly of Linear Terphenyl-dicarbonitrile Linkers on Ag(111)

Nucleation of ordered Fe islands on Al2O3/Ni3Al(111)

Monitoring Two-Dimensional Coordination Reactions: Directed Assembly of Co−Terephthalate Nanosystems on Au(111)

Long-range adsorbate interactions mediated by a two-dimensional electron gas

Imaging of electron potential landscapes on Au(111)

Interlayer exchange coupling in ordered Fe nanocluster arrays grown on Al2O3/Ni3Al(111)

Surface characterization of MnxGe1-x and CryMnxGe1-x-y dilute magnetic semiconductors

Microscopic View of Nucleation on Surfaces

Uniaxial 2D Superlattice of Fe-4 Molecular Magnets on Graphene

Microscopic view of epitaxial metal growth: nucleation and aggregation

Magnetic Moment and Anisotropy of Individual Co Atoms on Graphene

Interaction potential and hopping dynamics governing sliding friction

Changing Morphology of Metallic Monolayers Via Temperature-Controlled Heteroepitaxial Growth

Optical properties of size selected neutral Ag clusters: electronic shell structures and the surface plasmon resonance

Confinement of surface state electrons in Fabry-Perot resonators

Mapping Orbital-Resolved Magnetism in Single Lanthanide Atoms

High-coverage structures of carbon monoxide adsorbed on Pt(111) studied by high-pressure scanning tunneling microscopy