Publications de Harald Brune | EPFL Graph Search

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Designing systems with large magnetic anisotropy is critical to realize nanoscopic magnets. Thus far, the magnetic anisotropy energy per atom in single-molecule magnets and ferromagnetic films remains typically one to two orders of magnitude below the theoretical limit imposed by the atomic spin-orbit interaction. We realized the maximum magnetic anisotropy for a 3d transition metal atom by coordinating a single Co atom to the O site of an MgO(100) surface. Scanning tunneling spectroscopy reveals a record-h

We report on the structural and electronic properties of the Bi/Au(110)-1 x 4 surface, by combining scanning tunneling microscopy, angle-resolved photoemission spectroscopy, and first-principles calculations. The analysis of the precursor 1 x 8 moire struc ...

We investigate the effect of H adsorption on the magnetic properties of individual Co atoms on Pt(111) with scanning tunneling microscopy. For pristine Co atoms, we detect no inelastic features in the tunnel spectra. Conversely, CoH and CoH2 show a number of low-energy vibrational features in their differential conductance identified by isotope substitution. Only the fcc-adsorbed species present conductance steps of magnetic origin, with a field splitting identifying their effective spin as S-eff = 2 for Co

Capture numbers are used in models of nucleation and growth on surfaces, and have been widely applied to predict nucleation densities and other quantities via rate equations. In conventional nucleation theory, much effort has historically been expended on obtaining good expressions for capture numbers in the diffusion-limited case. However, recent experiments and calculations have shown that weak repulsive interactions between adsorbate atoms on relatively smooth (e.g., close-packed metal) surfaces may shif

Magnetochemistry recently emerged as a promising approach to control addressable spin arrays on surfaces. Here we report on the binding, spatial ordering, and magnetic properties of Fe on a highly regular Co-tetraphenylporphyrin (Co-TPP) template and highlight how the Fe controls the magnetism of the Co centers. As evidenced by scanning tunneling microscopy (STM) single Fe atoms attach to the saddle-shape conformers site-selectively in a unique coordination environment offered through a heptamer defined by

Regular arrays of single atoms with stable magnetization represent the ultimate limit of ultrahigh density storage media. Here we report a self-assembled superlattice of individual and noninteracting Dy atoms on graphene grown on Ir(111), with magnetic hysteresis up to 5.6 T and spin lifetime of 1000 s at 2.5 K. The observed magnetic stability is a consequence of the intrinsic low electron and phonon densities of graphene and the 6-fold symmetry of the adsorption site. Our array of single atom magnets has a

We report on a home-built detector for catalytic reaction measurements offering good gas isolation from the surrounding ultrahigh vacuum components, high sensitivity for reaction products and a fast response time of 10 ms enabling dynamic studies correlated to reactant gas pulses. The device is mounted in ultrahigh vacuum and combined with a low-temperature scanning tunneling microscope and a source for the deposition of mass-selected clusters. This combination allows for a direct correlation between surfac

The tribological behavior of carbon based thin films is strongly influenced by their chemical composition, polycrystalline structure and surface morphology. We present friction measurements on laser deposited amorphous carbon and carbon nitride (CNchi) thin films using atomic force microscopy. We studied the friction behavior of these films in relation with their structure and surface morphology resulting from the applied deposition parameters. We found high nanoscopic friction for amorphous carbon thin fil

We report on the synthesis, crystal structure and magnetic characterisation of the trinuclear, fluoride-bridged, molecular nanomagnet [Dy(hfac)(3)(H2O)-CrF2(py)(4)-Dy(hfac)(3)(NO3)] (1) (hfacH = 1,1,1,5,5,5-hexafluoroacetylacetone, py = pyridine) and a closely related dinuclear species [Dy(hfac)(4)-CrF2( py)(4)]center dot 1/2 CHCl3 (2). Element-specific magnetisation curves obtained on 1 by X-ray magnetic circular dichroism (XMCD) allow us to directly observe the field-induced transition from a ferrimagneti

The production of enantiopure materials and molecules is of uttermost relevance in research and industry in numerous contexts, ranging from nonlinear optics to asymmetric synthesis. In the context of the latter, dehalogenation, which is an essential reacti ...

We report magnetic hysteresis in Er clusters on. Cu(111) starting from the size-of three atoms. combining Xray magnetic circular dichroism, scanning tunneling microscopy, and mean-field nucleation theory, we determine the size dependent magnetic properties ...

The central goals of nanoscale magnetic materials science are the self-assembly of the smallest structure exhibiting ferromagnetic hysteresis at room temperature, and the assembly of these structures into the highest density patterns. The focus has been on ...

We present a scanning tunneling microscope operating in a 3He cryostat at a base temperature of 0.4 K, suitable for electron spin resonance (ESR) [S. Baumann, W. Paul, T. Choi, C. P. Lutz, A. Ardavan, and A. J. Heinrich, Science 350, 417 (2015)], quantum s ...

We present a detailed study on the strain-induced magnetic domain structure of a (La,Sr)MnO3 thin film epitaxially grown on a BaTiO3 substrate through the use of polarization-dependent X-ray photoemission electron microscopy and X-ray absorption spectroscopy. Angular-dependent measurements allow us to detect vector magnetization on a single-domain scale, and we relate the strain-induced changes in magnetic anisotropy of the ferromagnetic film to the ferroelectric domain structure of the underlying substrate

The self-assembly of sexiphenyl-dicarbonitrile molecules on the Ag(111) surface is investigated using low-temperature scanning tunneling microscopy (STM) in ultrahigh vacuum. Several nanoporous networks with varying symmetry and pore size coexist on the su ...

Ultrathin Fe films on Pt substrates have been investigated under ultrahigh vacuum conditions by scanning tunneling microscopy, low energy electron diffraction, magneto-optical Kerr effect, x-ray magnetic circular dichroism measurements, and Kerr microscopy ...

Nucleation and growth models are well developed for nucleation on homogeneous substrates, and they can typically be described-in terms of three energy parameters. Nucleation on substrates containing point-defect traps has been investigated, at the cost of introducing more energy parameters. This paper outlines the quantitative description of such growth models, using rate and rate-diffusion equations, in terms of energies for individual surface processes, with examples taken from metal-metal, metal-insulato

The original magnetic properties of nanometre-sized particles are due to the distinct contributions of volume, surface and step atoms. To disentangle these contributions is an ongoing challenge of materials science. Here we introduce a method enabling the identification. of the remarkably different contributions of surface and perimeter atoms to the magnetic anisotropy energy of two-dimensional nanostructures. Our method uses the generally nonlinear relationship between perimeter length and surface area. At

We report x-ray absorption spectroscopy and x-ray magnetic circular dichroism measurements as well as multiplet calculations for Dy, Ho, Er, and Tm atoms adsorbed on Pt(111), Cu(111), Ag(100), and Ag(111). In the gas phase, all four elements are divalent a ...

This invention relates to a device for emitting addressable locations comprises parallel spaced-apart first conductors (10) intersecting with parallel spaced-apart second conductors (11). The intersecting first and second conductors define addressable locations where electrons (12) are emitted in response to the application of an energizing voltage. One face of the first conductors is covered with an insulating layer (13) against which the second conductors (11) are applied, this insulating layer (13) formi

Harald Brune

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Reaching the magnetic anisotropy limit of a 3d metal atom

Structural and electronic properties of the Bi/Au(110)-1x4 surface

Controlling the Spin of Co Atoms on Pt(111) by Hydrogen Adsorption

Capture numbers in the presence of repulsive adsorbate interactions

Restoring the Co Magnetic Moments at Interfacial Co-Porphyrin Arrays by Site-Selective Uptake of Iron

Superlattice of Single Atom Magnets on Graphene

An experimental setup combining a highly sensitive detector for reaction products with a mass-selected cluster source and a low-temperature STM for advanced nanocatalysis measurements

Nanotribology of carbon based thin films: the influence of film structure and surface morphology

Direct observation of a ferri-to-ferromagnetic transition in a fluoride-bridged 3d–4f molecular cluster

Asymmetric Elimination Reaction on Chiral Metal Surfaces

Magnetic Hysteresis in Er Trimers on Cu(111)

Atomic-scale engineering of magnetic anisotropy of nanostructures through interfaces and interlines

A high bandwidth and high transmission STM bias line for ESR and quantum stochastic resonance measurements at 0.4 K

Strain-dependent magnetic configurations in manganite-titanate heterostructures probed with soft X-ray techniques

Self-Assembly of Nanoporous Chiral Networks with Varying Symmetry from Sexiphenyl-dicarbonitrile on Ag(111)

Structure and magnetism of atomically thin Fe layers on flat and vicinal Pt surfaces

Selective nucleation and controlled growth: quantum dots on metal, insulator and semiconductor surfaces

The remarkable difference between surface and step atoms in the magnetic anisotropy of two-dimensional nanostructures

4 f occupancy and magnetism of rare-earth atoms adsorbed on metal substrates

Hot electron emission array for e-beam photolithography and display screens