Publications de Harald Brune | EPFL Graph Search

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Element-specific magnetism accessible by synchrotron-based X-ray spectroscopy has proven to be valuable to study spin and orbital moments of transition metals and lanthanides in technologically relevant thin-film and monolayer samples. The access to cohere ...

The electrons of the surface states on the (I 11) surfaces of the noble metals An, Ag, and Cu form a quasi-two-dimensional (2D) free electron gas which is confined to the first few atomic layers at the crystal surface. They are scattered by the potential associated with surface defects, e.g. impurity atoms, adatoms, or step edges, leading to quantum-interference patterns in the local density of states around these defects, We have used the quantum-interference phenomena to quantitatively measure the electro

THE similarity of many patterns formed in non-equilibrium growth processes in physics, chemistry and biology is conspicuous, and many attempts have been made to discover common mechanisms underlying their formation(1). A central question is what causes some patterns to be dendritic (symmetrically branched, like snowflakes) and others fractal (randomly ramified). In general, the transition from fractal to dendritic growth is regarded as a manifestation of the predominance of anisotropy over random noise in t

We report on a novel approach to measure the phase relaxation length and femtosecond lifetime of hot quasiparticles on metal surfaces. A 4 K scanning tunneling microscope has been used to study the spatial decay of interference patterns in the local density of states for surface state electrons on Ag(111) and Cu(111). This decay is governed by inelastic; electron-electron scattering. We find a (E - E-F)(-2) energy dependence of the lifetimes for both Ag and Cu, and our values are comparable to the correspon

X-Treme is a soft X-ray beamline recently built in the Swiss Light Source at the Paul Scherrer Institut in collaboration with Ecole Polytechnique Federale de Lausanne. The beamline is dedicated to polarization-dependent X-ray absorption spectroscopy at hig ...

We examined by low-energy electron diffraction and scanning tunneling microscopy the surface of thin Cu films on Pt(111). The Cu/Pt lattice mismatch induces a moire modulation for films from 3 to about 10 ML thickness. We used angle-resolved photoemission ...

The low-temperature adsorption of isolated transition metal adatoms (Mn, Co, and Fe) onto hexagonal boron nitride monolayers on Rh(111) creates a bistable adsorption complex. The first state considerably weakens the hexagonal boron nitride- (h-BN-) substra ...

We describe a general method for the quantitative determination of the interlayer mass transport in epitaxial growth. Through measurement of the nucleation rate on top of islands as a function of island size and temperature, the additional barrier for an adatom to descend the step edge Delta E(s) can be determined with high accuracy. This approach is applied to the growth of Ag on the (111) surfaces of Ag and Pt. In the homoepitaxial system, the barrier is found to be Delta E(s) = 120 +/- 15 meV, whereas in

In the Kondo effect, a localized magnetic moment is screened by forming a correlated electron system with the surrounding conduction electrons of a non-magnetic host1. Spin S D 1=2 Kondo systems have been investigated extensively in theory and experiments, ...

We report on the magnetic properties of Fe and Co adatoms on a Cu2N/Cu(100)-c(2 x 2) surface investigated by x-ray magnetic dichroism measurements and density functional theory (DFT) calculations including the local coulomb interaction. We compare these results with properties formerly deduced from STM spin excitation spectroscopy (SES) performed on the individual adatoms. In particular we focus on the values of the local magnetic moments determined by XMCD compared to the expectation values derived from th

We report on the magnetic properties of individual Fe atoms deposited on MgO(100) thin films probed by x-ray magnetic circular dichroism and scanning tunneling spectroscopy. We show that the Fe atoms have strong perpendicular magnetic anisotropy with a zer ...

A permanent magnet retains a substantial fraction of its saturation magnetization in the absence of an external magnetic field. Realizing magnetic remanence in a single atom allows for storing and processing information in the smallest unit of matter. We s ...

Island densities and island sizes can be varied or even tailored by choice of external parameters in molecular beam epitaxy, i.e.: by the choice of substrate temperature. deposition rate, and coverage. We present a comprehensive study of the nucleation kinetics of Cu on Ni(100) using variable temperature scanning tunneling microscopy. The analysis of the saturation island density as a function of substrate temperature and deposition rate reveals that the smallest stable island abruptly changes from a dimer

Atomic scale engineering of magnetic fields is a key ingredient for miniaturizing quantum devices and precision control of quantum systems. This requires a unique combination of magnetic stability and spin-manipulation capabilities. Surface-supported singl ...

THE formation of nanometre-scale surface structures by atomic manipulation with the scanning tunneling microscope has opened up opportunities for creating new metastable states of matter atom by atom1. The technique allows the fabrication of arbitrary structures, but its application may be limited by considerations of speed, as only one nanostructure can be built at a time. Here we describe the simultaneous formation of many densely packed nanostructures of various morphologies using diffusion-controlled ag

A pivotal challenge in quantum technologies lies in reconciling long coherence times with efficient manipulation of the quantum states of a system. Lanthanide atoms, with their well-localized 4f electrons, emerge as a promising solution to this dilemma if ...

Mass selected Ag/sub n/ clusters (n=1,7,19) from a secondary ion source have been deposited onto a Pt(111) substrate at low temperature. The surface and resulting cluster morphology have subsequently been characterized within the same UHV chamber by variable temperature STM as a function of cluster size, kinetic impact energy, and substrate temperature. The kinetic energy per cluster atom was found to be the decisive parameter for a controlled deposition. Noble gas buffer layers ( approximately=10 ML Ar), w

The stability of magnetic information stored in surface adsorbed single-molecule magnets is of critical interest for applications in nanoscale data storage or quantum computing. The present study combines X-ray magnetic circular dichroism, density function ...

We use Ca doping during growth of one- and two-monolayer-thick MgO films on Ag(100) to identify the adsorption sites of individual adatoms with scanning tunnelingmicroscopy. For thiswe combine atomic resolution images of the bare MgO layer with images of t ...

Magneto-optical Kerr effect, is used to investigate the magnetization of film made of uncoalesced cobalt and cobalt-platinum nanocrystals. For the pure cobalt nanocrystals, different film morphologies are obtained through application of magnetic field during deposition. These morphologies have quite different magnetic properties, which is rationalized by considering dipolar interactions and the associated demagnetizing factor. We show that fast annealing can be used to trigger changes in the particles' crys

Harald Brune

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Element-specific X-Ray detection of electron paramagnetic resonance in thin films of quantum bits

Two-dimensional electron gas at noble-metal surfaces

Mechanism of the Transition from Fractal to Dendritic Growth of Surface Aggregates

Probing hot-electron dynamics at surfaces with a cold scanning tunneling microscope

X-Treme beamline at SLS: X-ray magnetic circular and linear dichroism at high field and low temperature

Electronic states of moiré modulated Cu films

Ring State for Single Transition Metal Atoms on Boron Nitride on Rh(111)

Interlayer Mass-Transport in Homoepitaxial and Heteroepitaxial Metal Growth

The role of magnetic anisotropy in the Kondo effect

Comparing XMCD and DFT with STM spin excitation spectroscopy for Fe and Co adatoms on

Origin of Perpendicular Magnetic Anisotropy and Large Orbital Moment in Fe Atoms on MgO

Magnetic remanence in single atoms

Submonolayer nucleation and growth of copper on Ni(100)

Engineering atomic-scale magnetic fields by dysprosium single atom magnets

Building One-Dimensional and 2-Dimensional Nanostructures by Diffusion-Controlled Aggregation at Surfaces

Electrically driven spin resonance of 4f electrons in a single atom on a surface

Hard and soft landing of mass selected Ag clusters on Pt(111)

Understanding the Superior Stability of Single-Molecule Magnets on an Oxide Film

Adsorption sites of individual metal atoms on ultrathin MgO(100) films

Magnetic properties of cobalt and cobalt-platinum nanocrystals investigated by magneto-optical Kerr effect