A5054718692- Topological Materials and Phenomena
- Physics of Superconductivity and Magnetism
- Quantum and electron transport phenomena
- Electronic and Structural Properties of Oxides
- Graphene research and applications
- Advanced Chemical Physics Studies
- Surface and Thin Film Phenomena
- Quantum many-body systems
- Magnetic properties of thin films
- Quantum, superfluid, helium dynamics
- Iron-based superconductors research
- Pulsars and Gravitational Waves Research
- Rare-earth and actinide compounds
- Quantum Mechanics and Non-Hermitian Physics
- Advanced Condensed Matter Physics
- Force Microscopy Techniques and Applications
- Organic and Molecular Conductors Research
- Inorganic Chemistry and Materials
- 2D Materials and Applications
- Magnetism in coordination complexes
- Superconducting Materials and Applications
- Quantum chaos and dynamical systems
- Diamond and Carbon-based Materials Research
University of Würzburg
2019-2025
Institute of Radio-Engineering and Electronics
2019
The coupling of a spin to an underlying substrate is the basis for plethora phenomena. In case metallic substrate, Kondo screening adatom magnetic moment can occur. As turns superconducting, intriguing situation emerges where pair breaking due spins leads Yu-Shiba-Rusinov bound states, but also intertwines with Through scanning tunneling spectroscopy, we analyze interdependence and superconductivity. Our data obtained on single Fe adatoms Nb(110) show that resulting YSR states are strongly...
We have studied cleaning procedures of Nb(110) by verifying the surface quality with low-energy electron diffraction, Auger spectroscopy, and scanning tunneling microscopy spectroscopy. Our results show that formation a surface-near impurity depletion zone is inhibited very high diffusivity oxygen in Nb host crystal which kicks at annealing temperatures as low few hundred degree Celsius. Oxygen can be removed from heating up to...
We show that sputter-annealing a multicomponent topological material (Pb 1− x Sn Se) enables reversible tuning of the chemical potential while preserving its properties and achieving an atomically smooth surface.
The scattering of superconducting pairs by magnetic impurities on a surface leads to sharp in-gap resonances known as Yu-Shiba-Rusinov (YSR) bound states. Similar the interference itinerant electrons scattered defects in normal metals, these reveal periodic texture around impurity. wavelength is, however, often too short be resolved even methods capable atomic resolution, i.e., scanning tunneling microscopy (STM). We combine CO molecule with cluster pre-attached an STM tip maximize both...
The hybridization of Yu-Shiba-Rusinov (YSR) states in dimers magnetic impurities leads to molecularlike bonding and antibonding modes. In many-impurity systems, the interaction gives rise YSR bands can even result formation a topologically nontrivial superconducting state, characterized by Majorana fermions at edges system. To obtain more detailed understanding these interactions, we investigate coupling short one-dimensional Fe chains on clean Nb(110). We observe splitting single-atom peaks...
We investigate the electronic properties of type-II superconducting Nb(110) in an external magnetic field. Scanning tunneling spectroscopy reveals a complex vortex shape which develops from circular via coffee bean-shaped to elliptical when decreasing energy edge gap Fermi level. This anisotropy is traced back local density states Caroli-de-Gennes-Matricon exhibits direction-dependent splitting. Oxidizing surface triggers transition clean dirty limit, quenches bound states, and leads...
Step edges of topological crystalline insulators can be viewed as predecessors higher-order topology, they embody one-dimensional edge channels embedded in an effective three-dimensional electronic vacuum emanating from the insulator. Using scanning tunneling microscopy and spectroscopy, we investigate behavior such Pb1-xSnxSe under doping. Once energy position step is brought close to Fermi level, observe opening a correlation gap. The experimental results are rationalized terms interaction...
The interaction of spin-polarized one-dimensional (1D) topological edge modes localized along single-atomic steps the crystalline insulator ${\mathrm{Pb}}_{0.7}{\mathrm{Sn}}_{0.3}\mathrm{Se}(001)$ has been studied systematically by scanning tunneling spectroscopy. Our results reveal that coupling adjacent sets in at a step-to-step distance ${d}_{\mathrm{ss}}\ensuremath{\le}25\text{ }\text{ }\mathrm{nm}$, resulting characteristic splitting single peak Dirac point spectra. Whereas energy...
SnTe belongs to the recently discovered class of topological crystalline insulators. Here, we study formation line defects which break symmetry by strain in thin films. Strained SnTe(111) films are grown molecular beam epitaxy on lattice and thermal expansion coefficient-mismatched CdTe. To analyze structural properties films, applied situ reflection high-energy electron diffraction, x-ray reflectometry, high-resolution reciprocal space mapping, scanning tunneling microscopy. This...
Chiral symmetry is a fundamental property with profound implications for the properties of elementary particles, that implies spectral (i.e. E => -E ) in their dispersion relation. In condensed matter physics, chiral frequently associated superconductors or materials hosting Dirac fermions such as graphene topological insulators. There, an emergent low-energy property, accompanied by symmetry. While can be broken crystal distortion external perturbations, survives. As presence does not...
Single cobalt atoms on the (111) surfaces of noble metals were for a long time considered prototypical systems Kondo effect in scanning tunneling microscopy experiments. Yet, recent first-principle calculations suggest that experimentally observed spectroscopic zero-bias anomaly (ZBA) should be interpreted terms excitations Co atom's spin and formation novel quasiparticle, spinaron, magnetic polaron resulting from interaction with conduction electrons, rather than resonance. Here we present...
We present a detailed study of the growth Bi films on superconducting Nb(110) substrates in dependence coverages and Nb surface quality. find that grows (110) orientation at low coverage equivalent to about five pseudomorphic monolayers (${\mathrm{ML}}^{\mathrm{ps}}$) clean Nb(110), but then undergoes structural transition Bi(111) below 8 ${\mathrm{ML}}^{\mathrm{ps}}$. Comparison with two oxygen-reconstructed surfaces, $\mathrm{Nb}{\mathrm{O}}_{x}$ phases I II, reveals film thickness which...
Scattering of superconducting pairs by magnetic impurities on a surface leads to sharp in-gap resonances, known as Yu-Shiba-Rusinov (YSR) bound states. Similarly the interference itinerant electrons scattered defects in normal metals, these resonances reveal periodic texture around impurity. However, wavelength is often too short be resolved even methods capable atomic resolution, like scanning tunneling microscopy (STM). Here, we combine CO molecule with cluster pre-attached an STM tip...
In this experimental study, we use scanning tunneling microscopy and spectroscopy to investigate Yu-Shiba-Rusinov states induced by 4f-shell rare-earth Gd adatoms on a superconducting Nb(110) surface. We engineer atom chains along the substrate's $[1\overline{1}0]$ $[001]$ directions, revealing distinct behaviors in differently oriented chains. $[1\overline{1}0]$-oriented exhibit spectroscopic features at their ends, identifying them as trivial edge states, while $[001]$-oriented display...
Step edges of topological crystalline insulators can be viewed as predecessors higher-order topology, they embody one-dimensional edge channels embedded in an effective three-dimensional electronic vacuum emanating from the insulator. Using scanning tunneling microscopy and spectroscopy we investigate behaviour such Pb$_{1-x}$Sn$_{x}$Se under doping. Once energy position step is brought close to Fermi level, observe opening a correlation gap. The experimental results are rationalized terms...