A5057982818- Magnetic properties of thin films
- Graphene research and applications
- Quantum and electron transport phenomena
- Surface and Thin Film Phenomena
- Magnetism in coordination complexes
- ZnO doping and properties
- Molecular Junctions and Nanostructures
- Magnetic and transport properties of perovskites and related materials
- Lanthanide and Transition Metal Complexes
- Magnetic Properties and Synthesis of Ferrites
- Advanced Chemical Physics Studies
- Topological Materials and Phenomena
- Rare-earth and actinide compounds
- Heusler alloys: electronic and magnetic properties
- Copper-based nanomaterials and applications
- Physics of Superconductivity and Magnetism
- Iron oxide chemistry and applications
- Porphyrin and Phthalocyanine Chemistry
- Shape Memory Alloy Transformations
- Advancements in Battery Materials
- Ga2O3 and related materials
- 2D Materials and Applications
- X-ray Diffraction in Crystallography
- Magnetic Properties and Applications
- Advanced NMR Techniques and Applications
University of Konstanz
2016-2025
University of Koblenz and Landau
2008
Technische Universität Dresden
2008
RWTH Aachen University
2001-2007
Westfälische Hochschule
2003
We report on angle-resolved photoemission studies of the electronic pi states high-quality epitaxial graphene layers a Ni(111) surface. In this system electron binding energy shows strong dependence magnetization reversal Ni film. The observed extraordinarily large shift up to 225 meV graphene-derived band peak position for opposite directions is attributed manifestation Rashba interaction between spin-polarized electrons in and effective electric field at graphene/Ni interface. Our findings...
In situ prepared ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}(100)$ thin films were studied by means of scanning tunneling microscopy (STM) and spin-polarized photoelectron spectroscopy (SP-PES). The atomically resolved $(\sqrt{2}\ifmmode\times\else\texttimes\fi{}\sqrt{2})R45\ifmmode^\circ\else\textdegree\fi{}$ wavelike surface atomic structure observed STM is explained based on density functional theory (DFT) ab initio atomistic thermodynamics calculations as a laterally distorted layer containing...
We report an element-specific investigation of electronic and magnetic properties the graphene/Ni(111) system. Using x-ray circular dichroism, occurrence induced magnetism carbon atoms in graphene layer is observed. attribute this moment to strong hybridization between C π Ni 3d valence band states. The net estimated be range 0.05–0.1 μB per atom.
This paper presents our work on the investigation of surface structure and electronic magnetic properties graphene layer lattice-matched a ferromagnetic material, Ni(111). Scanning tunneling microscopy imaging shows that perfectly ordered epitaxial layers can be prepared by elevated temperature decomposition hydrocarbons, with domains larger than terraces underlying In some exceptional cases, films do not show rotational alignment metal surface, leading to moiré structures small...
We report on an investigation of spin-polarized secondary electron emission from the chemically inert system: graphene/Ni(111). An ordered passivation graphene layer (monolayer graphite) was formed Ni(111) surface via cracking propylene gas. The spin polarization electrons obtained this system upon photoemission is only slightly lower than one clean Ni but does not change large oxygen exposure. These results suggest to use such passivated as a source stable against adsorption reactive gases.
The complex electronic properties of ${\mathrm{ZrTe}}_{5}$ have recently stimulated in-depth investigations that assigned this material to either a topological insulator or 3D Dirac semimetal phase. Here we report comprehensive experimental and theoretical study both structural ${\mathrm{ZrTe}}_{5}$, revealing the bulk is strong (STI). By means angle-resolved photoelectron spectroscopy, identify at top valence band surface state. dispersion these bands well captured by ab initio calculations...
Regularly sized Ni nanoclusters (NCs) have been grown on a graphene Moiré Rh(111). Using scanning tunneling microscopy, we determine that initial growth of at 150 K leads to preferential nucleation monodispersed NCs specific sites the superstructure. However, defined long-range ordering with increasing coverage is not observed. Room temperature deposition formation flat triangular-shaped islands which are well-matched registry.
We use in situ scanning tunneling microscopy (STM) to investigate intercalation of the ferromagnetic 3d metals Ni and Fe underneath a graphene monolayer on Rh(111). Upon thermal annealing graphene/Rh(111) with deposited metal top, we observe formation epitaxial monatomic nanoislands grown pseudomorphically Rh(111) covered by graphene. The size shape intercalated is strongly influenced local spatial variation graphene–Rh bonding strength. In particular, side length shows maxima around...
Here we report a photoemission study of the Fe intercalation underneath graphene layer on Ni(111). The process was monitored by means x-ray corresponding core levels as well ultraviolet graphene-derived π states in valence band. Thin fcc layers (2–5 ML thickness) at interface between capping and Ni(111) form epitaxial films passivated from reactive environment.
We present a detailed study of the spin-dependent electronic structure thin epitaxial magnetite films different crystallographic orientations. Using spin- and angle-resolved photoelectron spectroscopy at room temperature, we determine for Fe(3)O(4)(111) maximum spin polarization value -(80 ± 5)% near E(F). The spin-resolved spectra binding energies between 1.5 eV E(F) show good agreement with spin-split band from density functional theory (DFT) calculations which predict an overall energy...
The electronic and crystallographic structure of the graphene/Rh(111) moiré lattice is studied via combination density-functional theory calculations scanning tunneling atomic force microscopy (STM AFM). Whereas principal contrast between hills valleys observed in STM does not depend on sign applied bias voltage, atomically resolved AFM images strongly depends frequency shift oscillating tip. obtained results demonstrate perspectives application microscopy/spectroscopy for probing chemical...
Realization of graphene moir\'e superstructures on the surface 4d and 5d transition metals offers templates with periodically modulated electron density, which is responsible for a number fascinating effects, including formation quantum dots site selective adsorption organic molecules or metal clusters graphene. Here, applying combination scanning probe microscopy/spectroscopy density functional theory calculations, we gain profound insight into electronic topographic contributions to...
Abstract We investigate the electronic properties of graphene nanoflakes on Ag(111) and Au(111) surfaces by means scanning tunneling microscopy spectroscopy as well density functional theory calculations. Quasiparticle interference mapping allows for clear distinction substrate-derived contributions in scattering those originating from nanoflakes. Our analysis shows that parabolic dispersion surface states remains unchanged with band minimum shifted to higher energies regions metal covered...
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...
Single molecule magnets (SMMs) have attracted considerable attention due to low-temperature magnetic hysteresis and fascinating quantum effects. The investigation of these properties requires the possibility deposit well-defined monolayers or spatially isolated molecules within a well-controlled adsorption geometry. Here we present successful fabrication self-organized arrays Fe4 SMMs on hexagonal boron nitride (h-BN) Rh(111) as template. Using rational design ligand shell optimized for...
Addressing the multitude of electronic phenomena theoretically predicted for confined graphene structures requires appropriate in situ fabrication procedures yielding nanoflakes (GNFs) with well-defined geometries and accessible properties. Here, we present a simple strategy to fabricate quasi-free-standing GNFs variable sizes, performing temperature programmed growth flakes on Ir(111) surface subsequent intercalation gold. Using scanning tunneling microscopy (STM), show that epitaxial...
Epitaxial CrO2(100) island films have been grown on TiO2(100) substrates by a chemical-vapor deposition technique. Well-controlled surface and interface properties of the were confirmed scanning tunneling microscopy transmission electron microscopy, respectively. Spin- angle-resolved photoemission spectroscopy at room temperature revealed an energy gap about 2 eV below Fermi level EF for spin-down electrons spin polarization +95% EF. After extended sputtering, can be recovered from +10% up...
We present a detailed study on the electronic properties of monolayers ${\mathrm{Mn}}_{12}$ derivatives chemically grafted clean as well functionalized Au(111) surfaces. Scanning tunneling microscopy and x-ray photoelectron spectroscopy were employed to ensure successful monolayer deposition. Unoccupied occupied valence band states in structure ${\mathrm{Mn}}_{12}$-clusters probed by means absorption (XAS) resonant (RPES) at Mn $2p\text{\ensuremath{-}}3d$ edge, respectively. XAS measurements...
Abstract Single‐molecule magnets (SMMs) are among the most promising building blocks for future magnetic data storage or quantum computing applications, owing to bistability and long relaxation times. The practical device integration requires realization of 2D surface assemblies SMMs, where each unit shows being sufficiently slow at application‐relevant temperatures. Using X‐ray absorption spectroscopy circular dichroism, it is shown that sub‐monolayers Dy 2 @C 80 (CH Ph) dimetallofullerenes...
The electronic structure of high-quality ${\mathrm{CrO}}_{2}(100)$ films was investigated by means x-ray absorption and resonant photoemission spectroscopy at the $2p\text{\ensuremath{-}}3d$ excitation threshold. obtained binding energy occupied Cr $3d$ states is in agreement with results predicted within local spin-density approximation using dynamical mean-field theory [L. Craco et al., Phys. Rev. Lett. 90, 237203 (2003)]. reported data support a model ${\mathrm{CrO}}_{2}$ as half-metallic...
We report on a detailed study of structural, magnetic, and electronic properties MnxGe1−x single crystals (0<x<0.1) prepared by the Bridgman’s crystal growth technique. The chemical distribution Mn in Ge matrix investigated means energy dispersive x-ray spectroscopy indicates strong phase separation Ge/Mn system. Temperature-dependent magnetization [M(T)] measurements performed Mn-poor part containing 1%–3% reveal magnetic similar to those Mn11Ge8 reference sample as well...
We use time-resolved Faraday rotation spectroscopy to probe the electron spin dynamics in ZnO and magnetically doped Zn(1-x)Co(x)O sol-gel thin films. In undoped ZnO, we observe an anomalous temperature dependence of ensemble dephasing time T(2), i.e., longer coherence times at higher temperatures, reaching T(2) ∼ 1.2 ns room temperature. Time-resolved transmission measurements suggest that this effect arises from hole trapping grain surfaces. Deliberate addition Co(2+) increases effective...
Two-dimensional planar antiferromagnets on the basis of transition metal phosphorus trichalcogenides (MPX3) have recently attracted much attention owing to possibility exfoliating these materials and potentially implementing them in spintronic heterostructures. For purpose designing particular interfaces with graphene or other two-dimensional materials, knowledge real-space atomic distributions MPX3 layers is essential. Here, by using scanning probe microscopy combination ab initio...
The realization of single molecule-based electronic switching devices is an intriguing perspective on the path towards ultimate device miniaturization. In particular, integration multiple centers into a single...