A5071341075- Molecular Junctions and Nanostructures
- Quantum and electron transport phenomena
- Surface Chemistry and Catalysis
- Graphene research and applications
- Topological Materials and Phenomena
- Surface and Thin Film Phenomena
- Magnetic properties of thin films
- Electronic and Structural Properties of Oxides
- Advanced Condensed Matter Physics
- Physics of Superconductivity and Magnetism
- Catalytic Processes in Materials Science
- Porphyrin and Phthalocyanine Chemistry
- Magnetism in coordination complexes
- Quantum-Dot Cellular Automata
- Iron-based superconductors research
- Advanced Memory and Neural Computing
- Gold and Silver Nanoparticles Synthesis and Applications
- Plasmonic and Surface Plasmon Research
- Additive Manufacturing and 3D Printing Technologies
- Advanced Thermoelectric Materials and Devices
- Green IT and Sustainability
- Fuel Cells and Related Materials
- Electron Spin Resonance Studies
- Advanced Sensor and Energy Harvesting Materials
- Photorefractive and Nonlinear Optics
Material Physics Center
2015-2024
University of Cologne
2021-2024
Donostia International Physics Center
2016-2023
University of the Basque Country
2016-2019
Consejo Superior de Investigaciones Científicas
2016-2019
Universität Hamburg
2007-2015
By means of ab initio calculations and spin-polarized scanning tunneling microscopy experiments the creation a complex energy dependent magnetic structure with tailored interface is demonstrated. We show this novel effect by adsorbing organic molecules containing π(p(z)) electrons onto surface. The hybridization out-of-plane p(z) atomic-type orbitals d states metal leads to inversion spin polarization at site due p(z)-d Zener exchange-type mechanism. As key result, we demonstrate possibility...
We investigate the spin- and energy dependent tunneling through a single organic molecule (CoPc) adsorbed on ferromagnetic Fe thin film, spatially resolved by low-temperature spin-polarized scanning microscopy. Interestingly, metal ion as well ligand show significant spin-dependence of current flow. State-of-the-art ab initio calculations including also van-der-Waals interactions reveal strong hybridization molecular orbitals surface 3d states. The is anionic due to transfer one electron,...
Using spin-polarized scanning tunneling microscopy and density functional theory, we have studied the structural magnetic properties of cobalt-intercalated graphene on Ir(111). The cobalt forms monolayer islands being pseudomorphic with Ir(111) beneath graphene. strong bonding between leads to a high corrugation within Moir\'e pattern which arises due lattice mismatch Co intercalation regions exhibit an out-of-plane easy axis extremely switching field, surpasses significant values reported...
Light-matter interaction at the atomic scale rules fundamental phenomena such as photoemission and lasing while enabling basic everyday technologies, including photovoltaics optical communications. In this context, plasmons, collective electron oscillations in conducting materials, are important because they allow manipulation of fields nanoscale. The advent graphene other two-dimensional crystals has pushed plasmons down to genuinely dimensions, displaying appealing properties a large...
The temperature-dependent adsorption behavior of fourfold symmetric metal phthalocyanines $(M\text{Pcs})$ on metals with commensurate and incommensurate symmetries was investigated by scanning tunneling microscopy. On the Cu(100) surface, planar molecular structures in two equivalent orientations were found for $M\text{Pcs}$ when prepared at room temperature. In addition, metastable identified low temperature, which can be depopulated upon annealing. adsorbed sixfold Cu(111) surface showed a...
A molecular model system of tetraphenyl porphyrins (TPP) adsorbed on metallic substrates is systematically investigated within a joint scanning tunnelling microscopy/molecular modelling approach. The conformation TPP molecules, their adsorption gold surface and the growth highly ordered islands are modelled with combination density functional theory dynamic force field methods. results indicate subtle interplay between different contributions. molecule–substrate interaction causes bending...
Surface confined dehalogenation reactions are versatile bottom-up approaches for the synthesis of carbon-based nanostructures with predefined chemical properties. However, devices generally requiring low conductivity substrates, potential applications so far severely hampered by necessity a metallic surface to catalyze reactions. In this work we report ordered arrays poly(p-phenylene) chains on semiconducting TiO2(110) via dehalogenative homocoupling 4,4"-dibromoterphenyl precursors. The...
The family of topological superconductors derived from $\mathrm{Bi}_{2}\mathrm{Se}_{3}$, $\mathrm{Cu}_x(\mathrm{PbSe})_{5}(\mathrm{Bi}_{2}\mathrm{Se}_{3})_{6}$ is unique in its surface termination a single quintuple layer (QL) the insulator (TI) $\mathrm{Bi}_{2}\mathrm{Se}_{3}$ on an ordinary PbSe. Here, we report combined scanning tunneling microscopy (STM) and density functional theory (DFT) characterization cleaved parent compound $(\mathrm{PbSe})_{5}(\mathrm{Bi}_{2}\mathrm{Se}_{3})_{6}$...
We investigate molecule-molecule, as well molecule-substrate, interactions of phthalocyanine molecules deposited on graphene. In particular, we show how to tune the self-assembly molecular lattices in two dimensions by intercalation transition metals between graphene and Ir(111): modifying surface potential layer via leads formation square, honeycomb, or Kagome lattices. Finally, demonstrate that such induced are stable even at room temperature.
Organic–inorganic hybrid materials are of great demand not at least for their enormous application potential in flexible devices. Atomic or molecular layer deposition (ALD MLD) and vapor phase infiltration (VPI) offer novel pathways the fabrication such hybrids, but a clear understanding chemistry between vaporized precursors functional molecules is still lacking. In this work, interactions trimethylaluminum (TMA) organic groups OH, NH 2 , NO respective substituted phenyls, as well...
Graphene is an attractive material for its physicochemical properties, but many applications only chemically synthesized forms such as graphene oxide (GO) and reduced (rGO) can be produced in sufficient amounts. If considered electrode material, the intrinsic defects of GO or rGO may have negative influence on conductivity electrochemical properties. Such are commonly oxidized sites that offer possibility to functionalized with other materials order improve performance. In this work, we...
Making use of the inherent surface anisotropy different high index planes vicinal to low Au(111) orientation, one-dimensional polymers have been synthesized following established procedures from two precursor molecules. The successful polymerization both 4,4″-dibromo-p-terphenyl and 5,5′-dibromo-salophenato-Co(II) precursors into poly(p-phenylene) poly[salophenato-Co(II)], respectively, has confirmed by scanning tunneling microscopy energy electron diffraction. Angle-resolved photoemission...
The bottom-up synthesis of carbon-based nanomaterials directly on semiconductor surfaces allows for the decoupling their electronic and magnetic properties from substrates. However, typically reduced reactivity such nonmetallic adversely affects course these reactions. Here, we achieve a high polymerization yield halogenated polyphenyl molecular building blocks semiconducting TiO2(110) surface via concomitant decoration with cobalt atoms, which catalyze Ullmann coupling reaction....
The high reactivity of magnetic substrates toward molecular overlayers has so far inhibited the realization more sophisticated on-surface reactions, thereby depriving these interfaces a significant class chemically tailored organics such as graphene nanoribbons, oligonuclear spin-chains, and metal-organic networks. Here, we present multitechnique characterization polymerization 4,4″-dibromo-p-terphenyl precursors into ordered poly(p-phenylene) arrays on top bimetallic GdAu2 surface alloy....
Molecular spintronics is currently attracting a lot of attention due to its great advantages over traditional electronics. A variety self-assembled molecule-based devices are under development, but studies regarding the reliability growth process remain rare. Here, we present method control length molecular spintronic chains and make their terminations chemically inert, thereby suppressing uncontrolled coupling surface defects. The temperature evolution chain formation was followed by X-ray...
We report on spin-resolved measurements of single cobalt phthalocyanine molecules which are coupled to a ferromagnetic support. The same molecule is probed while the magnetization direction tip rotated from parallel antiparallel by application an external magnetic biasing field. Highly spin-polarized states near Fermi energy demonstrate realization spin filter. Intramolecular variations molecular polarization reveal resonance for ion as well carried organic ligand. measured sign support and...
As the characteristic length scale of devices continues to decrease, it is essential understand fundamental magnetic properties reduced dimension structures. This paper examines electronic and two-dimensional nanoscale Co islands on an Ir(111) surface using spin-polarized scanning tunneling microscopy. The pseudomorphic investigated are ferromagnetic single domain, with easy axis normal sample surface. Remarkably, coercivity these greater than 4 T saturation requires applied field at least 5 T.
A combined scanning tunneling microscopy, x-ray photoelectron spectroscopy, angle-resolved photoemission and density functional theory study of graphene on a Fe–Ir(111) alloy with variable Ir concentration is presented. Starting from an intercalated Fe layer between the Ir(111) surface we find that graphene–substrate interaction can be fine-tuned by Fe–Ir alloying at interface. When critical Ir-concentration close to 0.25 reached in layer, Dirac cone largely restored thereafter tuned across...
Tetraphenyl porphyrins (TPP) belong to a highly interesting class of molecules with large variety electronic, magnetic, and structural properties. So far, local investigations by scanning probe techniques were primarily focused on larger agglomerates TPP molecules. Here, experimental results the observation manipulation isolated adsorbed cold metal substrates means low temperature tunneling microscopy are presented. Depending surface geometry, i.e., Cu(111) vs Cu(100) three distinct...
Low dimensional carbon-based materials are interesting because they can show intrinsic $\pi$-magnetism associated to p-electrons residing in specific open-shell configurations. Consequently, during the last years there have been impressive advances field combining indirect experimental fingerprints of localized magnetic moments with theoretical models. In spite that, a characterization their spatial- and energy-resolved spin-moment has so far remained elusive. To obtain this information, we...