Publications de Harald Brune | EPFL Graph Search

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We studied by angle-resolved photoelectron spectroscopy the strain-related structural transition from a pseudomorphic monolayer (ML) to a striped incommensurate phase in an Ag thin film grown on Pt(111). We exploited the surfactant properties of Bi to grow ordered Pt(111)-xMLAg-Bi trilayers with 0

Due to the importance of scanning tunneling microscopy for atomic scale research the anomalously high corrugation values on close packed metal surfaces have been the subject of debate and extensive theoretical work in the past two decades. To date it remained unclear, how surface properties and electronic structures are related to forces and interactions. Here we show that elasticity, in particular the high elasticity of aluminum surfaces, enhances corrugation by up to one order of magnitude. The parameter-

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 (similar to 3x10(12)cm(-2)) were observed over a wide temperature range, indicating nucleation kinetics governed by point defects with a high trapping energy. These results are compared to a rate equation model that describes the principal atomistic nucleation and growth processes, including nucleation at attractive point defects.

We present an atomic force microscope study of nanoscopic sliding friction on diamond, diamond-like carbon, and on three CrN thin films with varying hardness obtained by different growth temperatures. For the CrN films, we show that the changes in the friction coefficient can be traced back to variations of the Young modulus. More generally, we show for all samples investigated and in wearless regime, that the nanoscopic friction coefficient is directly linked to the Young modulus. (C) 2003 American Institu

Magnetic atoms at surfaces are a rich model system for solid-state magnetic bits exhibiting either classical(1,2) or quantum(3,4) behaviour. Individual atoms, however, are difficult to arrange in regular patterns(1-5). Moreover, their magnetic properties a ...

Dispersion relations of the s-p derived surface state on (111) surfaces of silver and copper have been measured using low-temperature scanning tunneling microscopy and spectroscopy. For silver as well as for copper we find a significant deviation from a parabolic dispersion characteristic of free-electron-like systems. A simple tight-binding model accounts for the trends in the measured dispersions. (C) 2000 Elsevier Science B.V. All rights reserved.

We perform on-surface synthesis of single-ion molecular magnets on an Ag(111) surface and characterize their morphology, chemistry, and magnetism. The first molecule we synthesize is TbPc2 to enable comparison with chemically synthesized and subsequently s ...

We have investigated the influence of strain on the morphology in metal heteroepitaxy at temperatures where growth is dominated by kinetics. Whereas Ag(111) homoepitaxy is three dimensional below 400 K, the growth of Ag On Pt(111) proceeds two dimensionally up to a critical film thickness after which a transition to 3D growth is observed. This critical thickness increases from 1 ML at 130 K to 6-9 ML at 300 K. It is demonstrated that the 2D growth in the heteroepitaxial system is due to the particular growt

We demonstrate rotational excitation spectroscopy with the scanning tunneling microscope for physisorbed H-2 and its isotopes HD and D-2. The observed excitation energies are very close to the gas phase values and show the expected scaling with the moment of inertia. Since these energies are characteristic for the molecular nuclear spin states we are able to identify the para and ortho species of hydrogen and deuterium, respectively. We thereby demonstrate nuclear spin sensitivity with unprecedented spatial

We have studied the evolution of the magnetic properties of monolayer-high cobalt islands on a Pt(111) surface as function of their exposure to oxygen. We observe a sequential quenching of magnetic anisotropy and magnetic moment. For minute exposures to oxygen this leads to an enhancement of the maximum susceptibility of up to 66% for chi". We show that the reason for the reduction of the anisotropy before the one of the moment is due to preferential oxygen adsorption at the island edges, which are the main

The mechanism of strain relief for compressively stressed Ag layers epitaxially grown on Pt(111) is studied by scanning tunneling microscopy. The strain in the compressed commensurate (1X1) Ag monolayer on Pt(111) is relieved in the bilayer by the formation of two weakly incommensurate structures: the metastable striped incommensurate phase, which converts into a trigonal network of domain walls upon annealing. This network is a general case for isotropic strain relief realized by the crossing of domain wal

Intrinsically chiral surfaces of intermetallic compounds are shown to be novel materials for enantioselective processes. Their advantage is the significantly higher thermal and chemical stability, and therefore their extended application range for catalyzed chiral reactions compared to surfaces templated with chiral molecular modifiers or auxiliaries. On the Pd-1-terminated PdGa(111) surface, room-temperature adsorption of a small prochiral molecule (9-ethynylphenanthrene) leads to exceptionally high enanti

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- and shape-controlled open nanomeshes with pore dimensions up to 5.7 nm. Th ...

Clusters and islands of Fe atoms have been prepared by noble gas buffer layer assisted growth as well as by standard molecular beam epitaxy on Pt substrates. Xe buffer layers have been utilized to promote the formation of compact, relaxed Fe clusters with ...

We demonstrate that the giant spin contrast observed by scanning tunneling microscopy for double-layer Coislands on Pt(111) is caused by adsorbates at the apex of the Cr-coated W tip. The most likely candidate, in ab initio simulations, is hydrogen. Here, ...

Single atom magnets offer the possibility of magnetic information storage in the most fundamental unit of matter. Identifying the parameters that control the stability of their magnetic states is crucial to design novel quantum magnets with tailored proper ...

Graphene transfer methods either employ support layers that have to be removed after transfer, giving rise to impurities, or are based on delamination from bulk crystals, yielding only small flakes with various thicknesses. We present a graphene transfer m ...

We report on the magnetization reversal mechanism of Co islands on Pt(111) as a function of their size and shape. We measure the zero-field susceptibility chi(T) and low-temperature magnetization curves M(H) with in situ magneto-optical Kerr effect. Together with the island morphology deduced from scanning tunneling microscopy, this creates sufficient information to determine both the magnetization reversal mechanism and the distribution of anisotropy energies between perimeter and surface atoms. We find a

Low-temperature x-ray magnetic circular dichroism measurements on the endohedral single-molecule magnet DySc2N@C-80 at the Dy M-4,M-5 edges reveal a shrinking of the opening of the observed hysteresis with increasing x-ray flux. Time-dependent measurements show that the exposure of the molecules to x-rays resonant with the Dy M-5 edge accelerates the relaxation of magnetization more than off-resonant x-rays. The results cannot be explained by a homogeneous temperature rise due to x-ray absorption. Moreover,

During the sliding of an atomic force microscope (AFM) tip on a rough hydrophilic surface, water capillary bridges form between the tip and the asperities of the sample surface. These water bridges give rise to capillary and friction forces. We show that the capillary force increases with the normal load following a 2/3 power law. We trace back this behavior to the load induced change of the tip-surface contact area which determines the number of asperities where the bridges can form. An analytical relation

Harald Brune

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Ag-coverage-dependent symmetry of the electronic states of the Pt(111)-Ag-Bi interface: The ARPES view of a structural transition

The role of surface elasticity in giant corrugations observed by scanning tunneling microscopes

Nucleation and growth of supported clusters at defect sites: Pd/MgO(001)

Young modulus dependence of nanoscopic friction coefficient in hard coatings

Supramolecular control of the magnetic anisotropy in two-dimensional high-spin Fe arrays at a metal interface

Noble metal surface states: deviations from parabolic dispersion

Magnetic properties of on-surface synthesized single-ion molecular magnets

Strain mediated two-dimensional growth kinetics in metal heteroepitaxy: Ag/Pt(1111)

Distinction of Nuclear Spin States with the Scanning Tunneling Microscope

Oxidation induced enhanced magnetic susceptibility of Co islands on Pt(111)

Strain Relief at Hexagonal-Close-Packed Interfaces

Highly Enantioselective Adsorption of Small Prochiral Molecules on a Chiral Intermetallic Compound

Metal-organic honeycomb nanomeshes with tunable cavity size

Magnetism of Fe clusters and islands on Pt surfaces

Role of hydrogen in giant spin polarization observed on magnetic nanostructures

Correlation between Electronic Configuration and Magnetic Stability in Dysprosium Single Atom Magnets

Large Area Monolayer Graphene Transfer in Ultra-High Vacuum

Magnetization reversal mechanism of ramified and compact Co islands on Pt(111)

X-ray induced demagnetization of single-molecule magnets

The 2/3 power law dependence of capillary force on normal load in nanoscopic friction