A5056090435- Magnetic properties of thin films
- Surface and Thin Film Phenomena
- Quantum and electron transport phenomena
- Advanced Chemical Physics Studies
- Electron and X-Ray Spectroscopy Techniques
- Graphene research and applications
- Topological Materials and Phenomena
- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Rare-earth and actinide compounds
- X-ray Spectroscopy and Fluorescence Analysis
- Semiconductor materials and interfaces
- Magnetic and transport properties of perovskites and related materials
- Molecular Junctions and Nanostructures
- Electronic and Structural Properties of Oxides
- Advanced Materials Characterization Techniques
- Magnetism in coordination complexes
- Theoretical and Computational Physics
- Iron-based superconductors research
- ZnO doping and properties
- 2D Materials and Applications
- Chemical and Physical Properties of Materials
- Particle Accelerators and Free-Electron Lasers
- Copper Interconnects and Reliability
- Particle accelerators and beam dynamics
Institute of Structure of Matter
2016-2025
AREA Science Park
2005-2022
École de Technologie Supérieure
2022
Helmholtz-Zentrum Berlin für Materialien und Energie
2015
Institució Catalana de Recerca i Estudis Avançats
2009
Forschungszentrum Jülich
1996-2005
École Polytechnique Fédérale de Lausanne
2002-2003
Max Planck Institute for Solid State Research
2003
European Synchrotron Radiation Facility
2003
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati
2003
The isotropic magnetic moment of a free atom is shown to develop giant anisotropy energy due symmetry reduction at an atomically ordered surface. Single cobalt atoms deposited onto platinum (111) are found have 9 millielectron volts per arising from the combination unquenched orbital moments (1.1 Bohr magnetons) and strong spin-orbit coupling induced by substrate. By assembling nanoparticles containing up 40 atoms, further be dependent on single-atom coordination changes. These results...
We report on the electronic properties of straight, 1.6 nm wide, silicene nanoribbons Ag(110), arranged in a one-dimensional grating with pitch 2 nm, whose high-resolution scanning tunneling microscopy images reveal honeycomb geometry. Angle-resolved photoemission shows quantum confined states character. The silicon band dispersion along direction suggests behavior analogous to Dirac cones graphene different substrates.
The electronic and magnetic character of epitaxial Fe films on Ag(001) has been studied as a function coverage by spin- angle-resolved photoemission with synchrotron radiation. At coverages well below monolayer, the spectra exhibit local spin-split state. Although for in monolayer range display structure close agreement calculated film critical-point energies, no spin polarization is observed up to 2.5 monolayers coverage. Thicker approach bulk Fe(001).
By spin resolved photoemission we have detected exchange-split spin-polarized electronic states in a nonmagnetic material deposited on magnetic substrate. Epitaxial Cu overlayers fcc Co(100) exhibit sp symmetry which are polarized by the confining interface. These can be observed up to film thickness of at least 10 atomic layers. The spectral polarization and intensity Fermi level display periodicity correlated with oscillations long range coupling between films separated Cu(100)
Spin-polarized low-energy electron diffraction is applied for the first time to study coupling between ferromagnetic and antiferromagnetic ultrathin films. The remanent magnetization epitaxial double-layer structure ${\mathrm{Fe}}_{\mathrm{ii}}$/Cr/${\mathrm{Fe}}_{\mathrm{i}}$/Cr(100) has been monitored in situ during growth. two Fe slabs (${\mathrm{Fe}}_{\mathrm{ii}}$, ${\mathrm{Fe}}_{\mathrm{i}}$) separated by a thin Cr layer show in-plane antiparallel magnetic along external field...
We investigate the hierarchy of local correlation and hybridization effects in metal-organic molecules adsorbed on metals. Using x-ray magnetic circular dichroism ligand field multiplet calculations, we demonstrate that 3$d$ electronic ground state monolayer metal-phthalocyanine (CoPc, FePc) Au(111) is given by coherent superposition two charge states, ${d}^{n}E+{d}^{n+1}$, where $E$ represents a substrate electron antiferromagnetically coupled to central metal ion ${d}^{n}$ many-body ionic...
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 moiré pattern formed on Ir(111). Angle-resolved photoemission spectroscopy reveals threefold symmetry band structure associated with strong renormalization of electron group velocity close Dirac point giving rise highly anisotropic cones. further find that superlattice also affects spectral-weight distribution carbon...
The discovery of (4×4) silicene formation on Ag(111) raised the question whether maintains its Dirac fermion character, similar to graphene, a supporting substrate. Previous photoemission studies indicated that π band forms cones near Fermi energy, while theoretical investigations found it shifted at deeper binding energy. By means angle-resolved spectroscopy and density-functional theory calculations we show instead π-symmetry states lose their local character cone fades out. an interface...
X-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) have been used to study transition metal impurities on K Na films. The multiplet structure of the XAS spectra indicates that Fe, Co, Ni localized atomic ground states with predominantly d7, d8, d9 character, respectively. XMCD shows impurity possess large, atomiclike, orbital moments are progressively quenched as clusters formed. films found be nonmagnetic, a strongly increased d10 character state. results show...
One-dimensional Co atomic wires grown on Pt(997) have been investigated by x-ray magnetic circular dichroism. Strong changes of the properties are observed as system evolves from 1D- to 2D-like. The easy axis magnetization, anisotropy energy, and coercive field oscillate a function transverse width wires, in agreement with theoretical predictions for 1D metal systems.
The magnetism of a Cu-phthalocyanine (CuPc) monolayer on Ag(100) was investigated using x-ray magnetic circular dichroism (XMCD) and ligand-field multiplet calculations. Contrary to other metal-Pc adsorbed metals, we show that the local CuPc moment survives interaction with electronic states substrate presents enhanced susceptibility respect bulk powder samples. Our measurements reveal extraordinary orbital anisotropy (500%) an anisotropic spin dipole up twice isotropic in metal-organic...
A photoemission study of the electronic structure a single graphene layer on nickel shows that electrons in with broken lattice symmetry still move like massless particles, contrary to what is expected.
Silicene, the silicon equivalent of graphene, is attracting increasing scientific and technological attention in view exploitation its exotic electronic properties. This novel material has been theoretically predicted to exist as a free-standing layer low-buckled, stable form, can be synthesized by deposition Si on appropriate crystalline substrates. By employing low-energy electron diffraction microscopy, we have studied growth Ag(1 1 1) observed rich variety rotationally non-equivalent...
We investigate the effects of Na adsorption on electronic structure bare and Ir cluster superlattice-covered epitaxial graphene Ir(111) using angle-resolved photoemission spectroscopy scanning tunneling microscopy. At saturation coverage, a massive charge migration from sodium atoms to raises Fermi level by ∼1.4 eV relative its neutrality point. find that is adsorbed top layer, when coadsorbed onto an superlattice, it results in opening large band gap ΔNa/Ir/G = 740 meV, comparable one Ge...
The spin state of organic-based magnets at interfaces is to a great extent determined by the organic environment and nature spin-carrying metal center, which further subject modifications adsorbate-substrate coupling. Direct chemical doping offers an additional route for tailoring electronic magnetic characteristics molecular magnets. Here we present systematic investigation effects alkali on charge crystal field 3d ions in Cu, Ni, Fe, Mn phthalocyanine (Pc) monolayers adsorbed Ag. Combined...
We report the discovery of a temperature-induced phase transition between α and β structures antimonene. When antimony is deposited at room temperature on bismuth selenide, it forms domains α-antimonene having different orientations with respect to substrate. During mild annealing, grows prevails over phase, eventually forming single domain that perfectly matches surface lattice structure selenide. First-principles thermodynamics calculations this van der Waals heterostructure explain...
The interplay between magnetism and chemistry at the Fe/Si(100) interface has been examined by spin- angle-resolved photoemission. A ferromagnetically ordered metallic silicide of \ensuremath{\sim}20 $\AA{}$ thickness is formed deposition Fe on Si room temperature. This layer ferromagnetic in-plane with a reduced spin polarization in comparison to bulk Fe. Its electronic structure indicates an Fe-rich composition close ${\mathrm{}\mathrm{Fe}}_{3}\mathrm{Si}$. Fe/Si Si/Fe are inequivalent...
We present a combined theoretical and experimental investigation of the electron properties calcium silicides (${\mathrm{Ca}}_{2}$Si, CaSi, ${\mathrm{CaSi}}_{2}$). The study is performed by self-consistent calculation states, while analysis based on synchrotron-radiation photoemission measurements. overall agreement between computed measured spectra allows us to investigate main features Ca-Si interaction in different compounds. find that covalent character bond strength this increases with...
We report on the structural and electronic properties of an artificial graphene/Ni(111) system obtained by intercalation a monatomic layer Ni in graphene/Ir(111). Upon intercalation, grows epitaxially Ir(111), resulting lattice-mismatched graphene/Ni system. By performing scanning tunneling microscopy measurements density functional theory calculations, we show that intercalated leads to pronounced buckling graphene film. At same time, enhanced interaction is measured angle-resolved...
The quantum anomalous Hall effect (QAHE) has recently been reported to emerge in magnetically doped topological insulators. Although its general phenomenology is well established, the microscopic origin far from being properly understood and controlled. Here, we report on a detailed systematic investigation of transition metal (TM) ${\mathrm{Sb}}_{2}{\mathrm{Te}}_{3}$. By combining density functional theory calculations with complementary experimental techniques, i.e., scanning tunneling...
Silicene, a honeycomb lattice of silicon, presents particular case allotropism on Ag(111). Silicene forms multiple structures with alike in-plane geometry but different out-of-plane atomic buckling and registry to the substrate. Angle-resolved photoemission first-principles calculations show that these silicene structures, (4×4), (√13×√13)R13.9°, (2√3×2√3)R30° periodicity, display similar electronic bands despite structural differences. In all cases interaction substrate modifies states,...
Antimonene, the two-dimensional phase of antimony, appears in two distinct allotropes when epitaxially grown on Bi2Se3: puckered asymmetric washboard (α) and buckled honeycomb (β) bilayer structures. As-deposited antimony films exhibit varying proportions single α β We identify conditions necessary for ordered, pure-phase growth to triple β-antimonene bilayers. Additionally, we determine their electronic structure, work function, characteristic core-level binding energies, offering an...
Half a monolayer (ML) of Mn deposited above 270 K on the (100) surfaces Cu and Ni form ordered surface alloys c(2\ifmmode\times\else\texttimes\fi{}2) structure. Their electronic structure is studied in combined experimental theoretical work. The approach, comprising angle-resolved photoemission inverse photoemission, characterizes both systems as ideal cases well-ordered magnetic alloys. A large atomiclike splitting between majority- minority-spin Mn-3d states measured: 5.5 eV for Cu-based...