Publications de Harald Brune | EPFL Graph Search

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We report on the magnetic properties of two-dimensional Co nanoparticles arranged in macroscopically phase-coherent superlattices created by self-assembly on Au(788). Our particles have a density of 26 Tera/in(2) (1 Tera=10(12)), are monodomain, and have u ...

We investigated the magnetic properties of individual Ho atoms adsorbed on the (111) surface of Pt, which have been recently claimed to display single ion magnetic behavior. By combining x-ray absorption spectroscopy and magnetic dichroism measurements with ligand field multiplet calculations, we reveal a ground state which is incompatible with long spin relaxation times, in disagreement with former findings. A comparative study of the ground state and magnetic anisotropy of Ho and Er on Pt(111) and Cu(111)

We determine the magnetic properties of individual Co atoms adsorbed on graphene (G) with x-ray absorption spectroscopy and magnetic circular dichroism. The magnetic ground state of Co adatoms strongly depends on the choice of the metal substrate on which graphene is grown. Cobalt atoms on G/Ru(0001) feature exceptionally large orbital and spin moments, as well as an out-of-plane easy axis with large magnetic anisotropy. Conversely, the magnetic moments are strongly reduced for Co/G/Ir(111), and the magneti

The recent development of temperature controlled scanning tunneling microscopy opened the door to a fascinating new world on the nanometer scale. The atomic scale information obtained provides unprecedented insight into the kinetics of surface phenomena such as epitaxial growth or chemisorption. In particular, a rich variety of surface structures could be observed, whose morphologies are determined by the self-assembly of the adsorbed particles. Temperature control allows for detailed investigations of the

In sharp contrast to previous studies on FeRh bulk, thin films, and nanoparticles, we report the persistence of ferromagnetic order down to 3 K for size-selected 3.3 nm diameter nanocrystals embedded into an amorphous carbon matrix. The annealed nanopartic ...

We investigate the spin relaxation of Ho single atom magnets on MgO/Ag(100) as a function of temperature and magnetic field. We find that the spin relaxation is thermally activated at low field, while it remains larger than 1000 s up to 30 K and 8 T. This ...

Lanthanide atoms show long magnetic lifetimes because of their strongly localized 4f electrons, but electrical control of their spins has been difficult because of their closed valence shell configurations. We achieved electron spin resonance of individual ...

The kinetics of molecular adsorption and desorption can unveil the details of the adsorption potential that impact, for instance, the overall sticking probability. This information is of particular importance for catalysis and gas sensing. We investigate t ...

CO adsorption on Pd atoms deposited on MgO(100) thin films has been studied by means of thermal desorption (TDS) and Fourier transform infrared (FTIR) spectroscopies. CO desorbs from the adsorbed Pd atoms at a temperature of about 250 K, which corresponds to a binding energy, E-b, of about 0.7 +/- 0.1 eV. FTIR spectra suggest that at saturation two different sites for CO adsorption exist on a single Pd atom. The vibrational frequency of the most stable, singly adsorbed CO molecule is 2055 cm(-1). Density fu

We present a new method to engineer the charge carrier mobility and its directional asymmetry in epitaxial graphene by using metal cluster superlattices self-assembled onto the moiré pattern formed by graphene on Ir(111). Angle-resolved photoemission spectroscopy reveals threefold symmetry in the band structure associated with strong renormalization of the electron group velocity close to the Dirac point giving rise to highly anisotropic Dirac cones. We further find that the cluster superlattice also affect

We investigated the electronic structure of epitaxially grown silver films on Cu(111) with and without adsorption of cesium by means of scanning tunneling spectroscopy and two-photon photoemission. This system has been chosen as a model system to engineer and measure the dynamics of charge-transfer processes between an adsorbate and a heterogeneous substrate. Special emphasis has been laid on the investigation of the energy shift of the Shockley-type surface state and an excited cesium resonance as a functi

High-density arrays (5 x 10(6) cm(-1)) of parallel nanowires have been grown using the vicinal Pt(997) surface as a template. Single monatomic rows of Ag and Cu can be deposited with subrow precision. We demonstrate real-time monitoring and characterization of the growth of the atomic chains as a function of temperature by thermal energy helium atom scattering. Scanning tunneling microscopy provides further insight into the structure of the metal rows. Growth mode and alloying with the Pt substrate are disc

A detailed study of the nucleation and growth of Cu on Ni(100) as a function of substrate temperature and deposition rate by variable temperature STM is reported. By the quantitative analysis of the saturation island density as a function of temperature and flux for submonolayer coverages, we have deduced the migration barrier (0.35 eV), the dimer bond energy (0.46 eV) as well the sizes of the the critical nuclei. Because the dimer bond energy is large with respect to the migration barrier, a well-defined t

The structural and electronic properties of a Pb monolayer (ML) grown on Au(111) are investigated by scanning tunneling microscopy (STM) and angle resolved photoelectron spectroscopy (ARPES). We find an incommensurate Moire structure with an approximate (5 ...

Spin-polarized scanning tunneling microscopy (SP-STM) measures magnetoresistance with atomic resolution. While various methods for achieving SP probes have been developed, each is limited with respect to fabrication, performance, and operating conditions. ...

We performed a combined theoretical and experimental investigation of the orbital magnetism and magnetocrystalline anisotropy of isolated Co and Fe adatoms on Pd(111) and Rh(111). Theoretical calculations of the spin and orbital moments are based on ab ini ...

The isotropic magnetic moment of a free atom is shown to develop giant magnetic anisotropy energy due to symmetry reduction at an atomically ordered surface. Single cobalt atoms deposited onto platinum ( 111) are found to have a magnetic anisotropy energy of 9 millielectron volts per atom arising from the combination of unquenched orbital moments (1.1 Bohr magnetons) and strong spin-orbit coupling induced by the platinum substrate. By assembling cobalt nanoparticles containing up to 40 atoms, the magnetic a

This Feature Article reports on the controlled formation and structure-functionality aspects of vacuum-deposited self-assembled organic and metal-organic networks at metal surfaces using ditopic linear and nonlinear molecular bricks, namely di-carbonitrile ...

We present a critical view of the analysis of experimental island densities acquired as a function of temperature in terms of barriers and prefactors for tracer diffusion at surfaces. We investigate the achievable precision for methods ranging from simple application of scaling laws, via integration of mean-held rate equations within various approximations for the capture rates, to kinetic Monte Carlo simulations that account for the various island shapes realized on square and hexagonal lattices. The discu

We report on low-temperature scanning tunneling microscopy observations demonstrating that individual Ti atoms on hexagonal boron nitride dissociate and adsorb hydrogen without measurable reaction barrier. The clean and hydrogenated states of the adatoms a ...

Harald Brune

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Uniform magnetic properties for an ultrahigh-density lattice of noninteracting Co nanostructures

Magnetism of Ho and Er Atoms on Close-Packed Metal Surfaces

Tailoring the Magnetism of Co Atoms on Graphene through Substrate Hybridization

Self-assembly at metal surfaces

Low Temperature Ferromagnetism in Chemically Ordered FeRh Nanocrystals

Unconventional Spin Relaxation Involving Localized Vibrational Modes in Ho Single-Atom Magnets

Direct Electrical Access to the Spin Manifolds of Individual Lanthanide Atoms

Reverse Spillover Dominating CO Adsorption on Single Cobalt Atoms in Graphene Divacancies

Identification of defect sites on MgO(100) thin films by decoration with Pd atoms and studying CO adsorption properties

Highly Anisotropic Dirac Cones in Epitaxial Graphene Modulated by an Island Superlattice

Electronic surface structure of n-ML Ag/Cu(111) and Cs/n-ML Ag/Cu(111) as investigated by 2PPE and STS

One-dimensional metal chains on Pt vicinal surfaces

Nucleation and growth of Cu/Ni(100): A variable temperature STM study

Combined ARPES and STM study of Pb/Au(111) Moiré structure: One overlayer, two symmetries

Antiferromagnetic MnNi tips for spin-polarized scanning probe microscopy

Magnetocrystalline anisotropy energy of Co and Fe adatoms on the (111) surfaces of Pd and Rh

Giant magnetic anisotropy of single cobalt atoms and nanoparticles

Surface-Confined Self-Assembly of Di-carbonitrile Polyphenyls

Measuring surface diffusion from nucleation island densities

Quantifying residual hydrogen adsorption in low-temperature STMs