A5008550693- Quantum and electron transport phenomena
- Magnetic properties of thin films
- Physics of Superconductivity and Magnetism
- Surface and Thin Film Phenomena
- Molecular Junctions and Nanostructures
- Topological Materials and Phenomena
- Electronic and Structural Properties of Oxides
- Advanced Memory and Neural Computing
- Force Microscopy Techniques and Applications
- 2D Materials and Applications
- Graphene research and applications
- Theoretical and Computational Physics
- Quantum many-body systems
- Advanced Condensed Matter Physics
- Atomic and Subatomic Physics Research
- Advanced Chemical Physics Studies
- Integrated Circuits and Semiconductor Failure Analysis
- Surface Chemistry and Catalysis
- Semiconductor materials and devices
- Chemical and Physical Properties of Materials
- Advanced Thermoelectric Materials and Devices
- Machine Learning in Materials Science
- Neural dynamics and brain function
- Iron-based superconductors research
- Quantum, superfluid, helium dynamics
Radboud University Nijmegen
2016-2025
Radboud Institute for Molecular Life Sciences
2016-2024
Radboud University Medical Center
2016-2024
Universität Hamburg
2009-2018
Hamburg Institut (Germany)
2014
The University of Texas at Austin
2004-2011
University of California, Santa Cruz
2004
Massachusetts Institute of Technology
2004
An ultimate goal of spintronic research is the realization concepts for atomic-scale all-spin-based devices. We combined bottom-up atomic fabrication with spin-resolved scanning tunneling microscopy to construct and read out model systems performing logic operations. Our concept uses substrate-mediated indirect exchange coupling achieve logical interconnection between individual spins. Combined spin frustration, this enables various operations inputs, such as NOT OR.
The future of nanoscale spin-based technologies hinges on a fundamental understanding and dynamic control atomic-scale magnets. role the substrate conduction electrons dynamics supported atomic magnets is still question interest lacking experimental insight. We characterized temperature-dependent dynamical response artificially constructed magnets, composed few exchange-coupled spins adsorbed metallic substrate, to spin-polarized currents driven read out by magnetic scanning tunneling...
The robustness of the gapless topological surface state hosted by a 3D insulator against perturbations magnetic origin has been focus recent investigations. We present comprehensive study properties Fe impurities on prototypical Bi$_2$Se$_3$ using local low temperature scanning tunneling microscopy and integral x-ray circular dichroism techniques. Single adatoms surface, in coverage range $\approx 1%$ are heavily relaxed into exhibit easy axis within surface-plane, contrary to what was...
We have performed single-atom magnetization curve (SAMC) measurements and inelastic scanning tunneling spectroscopy (ISTS) on individual Fe atoms a Cu(111) surface. The SAMCs show broad distribution of magnetic moments with 3.5 μB being the mean value. ISTS reveals excitation lifetime 200 fsec which decreases by factor 2 upon application field 12 T. experimental observations are quantitatively explained decay into Stoner modes itinerant electron system as shown newly developed theoretical modeling.
The electronic structure of epitaxial single-layer MoS$_2$ on Au(111) is investigated by angle-resolved photoemission spectroscopy, scanning tunnelling and first principles calculations. While the band dispersion supported close to a free-standing layer in vicinity valence maximum at $\bar{K}$ calculated gap similar that for layer, significant modifications are observed other points two-dimensional Brillouin zone: At $\bar{\Gamma}$, has significantly higher binding energy than free expected...
Utilizing a combination of low-temperature scanning tunneling microscopy/spectroscopy (STM/STS) and electronic structure calculations, we characterize the structural properties single atomic vacancies within several monolayers surface black phosphorus. We illustrate, with experimental analysis tight-binding that can depth profile these assign them to specific sublattices unit cell. Measurements reveal exhibit strongly anisotropic highly delocalized charge density, laterally extended up 20...
A combined experimental and theoretical study of doping individual Fe atoms into ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ is presented. It shown through a scanning tunneling microscopy that single initially located at hollow sites on top the surface (adatoms) can be incorporated subsurface layers by thermally activated diffusion. Angle-resolved photoemission spectroscopy in combination with ab initio calculations suggest behavior changes from electron donation for adatom to neutral or acceptance...
Single-layer ${\mathrm{TaS}}_{2}$ is epitaxially grown on Au(111) substrates. The resulting two-dimensional crystals adopt the $1H$ polymorph. electronic structure determined by angle-resolved photoemission spectroscopy and found to be in excellent agreement with density functional theory calculations. single-layer strongly $n$ doped, a carrier concentration of $0.3(1)$ extra electrons per unit cell. No superconducting or charge wave state observed scanning tunneling microscopy at...
A magnetic atom in a superconducting host induces so-called Yu-Shiba-Rusinov (YSR) bound states inside the energy gap. By combining spin-resolved scanning tunneling spectroscopy with simulations we demonstrate that pair of peaks associated YSR an individual Fe coupled to oxygen-reconstructed Ta surface gets spin polarized external field. As theoretically predicted, electron and hole parts have opposite signs polarizations which keep their character when crossing Fermi level through quantum...
Bottom-up quantum simulators have been developed to quantify the role of various interactions, dimensionality, and structure in creating electronic states matter. Here, we demonstrated a solid-state simulator emulating molecular orbitals, based solely on positioning individual cesium atoms an indium antimonide surface. Using scanning tunneling microscopy spectroscopy, combined with ab initio calculations, showed that artificial could be made from localized created patterned rings. These...
We have probed the local thermoelectric power of semiconductor nanostructures with use ultrahigh-vacuum scanning microscopy. When applied to a p-n junction, this method reveals that changes its sign abruptly within 2 nanometers across junction. Because correlates electronic structure, we can profile nanometer spatial resolution power, band structures, and carrier concentrations junctions constitute building blocks thermoelectric, electronic, optoelectronic devices.
We demonstrate using inelastic scanning tunneling spectroscopy and simulations based on density functional theory that the amplitude sign of magnetic anisotropy energy for a single Fe atom adsorbed onto Pt(111) surface can be manipulated by modifying adatom binding site. Since magnitude measured is remarkably small, up to an order smaller than previously reported, electron-hole excitations are weak thus spin excitation exhibits long lived precessional lifetimes compared values found same...
Abstract Chiral magnets are a promising route towards dense magnetic storage technology due to their inherent nano-scale dimensions and energy efficient properties. Engineering chiral requires atomic-level control of the exchange interactions, including Dzyaloshinskii–Moriya interaction, which defines rotational sense for magnetization two coupled moments. Here we show that indirect conduction electron-mediated interaction between individual atoms on metallic surface can be manipulated by...
The pathway toward the tailored synthesis of materials starts with precise characterization conformational properties and dynamics individual molecules. Electron spin resonance (ESR)-based scanning tunneling microscopy can potentially address molecular structure unprecedented resolution. Here, we determine fine geometry an titanium-hydride molecule, utilizing a combination newly developed millikelvin ESR microscope in vector magnetic field ab initio approaches. We demonstrate strikingly...
BCS theory has been widely successful at describing elemental bulk superconductors. Yet, as the length scales of such superconductors approach atomic limit, dimensionality well environment superconductor can lead to drastically different and unpredictable superconducting behavior. Here, we report a threefold enhancement critical temperature gap size in ultrathin epitaxial Al films on Si(111), when approaching 2D based high-resolution scanning tunneling microscopy/spectroscopy (STM/STS)...
Abstract Considering the growing interest in magnetic materials for unconventional computing, data storage, and sensor applications, there is active research not only on material synthesis but also characterisation of their properties. In addition to structural integral characterisations, imaging magnetisation patterns, current distributions fields at nano- microscale major importance understand responses qualify them specific applications. this roadmap, we aim cover a broad portfolio...
Rubidium adsorption on the surface of topological insulator Bi2Se3 is found to induce a strong downward band bending, leading appearance quantum-confined two-dimensional electron gas state (2DEG) in conduction band. The 2DEG shows Rashba-type spin–orbit splitting, and it has previously been pointed out that this relevance nanoscale spintronics devices. Rb atoms, other hand, renders very reactive, exposure oxygen leads rapid degrading 2DEG. We show intercalating presumably into van der Waals...
Whether rare-earth materials can be used as single-atom magnetic memory is an ongoing debate in recent literature. Here we show, by inelastic and spin-resolved scanning tunnelling-based methods, that observe a strong signal excitation from Fe atoms adsorbed on Pt(111), but see no signatures of or spin-based telegraph noise for Ho atoms. Moreover, the indirect exchange field produced single atom negligible, sensed nearby We demonstrate, using ab initio this stems comparatively weak coupling...