A5035643622- Graphene research and applications
- 2D Materials and Applications
- Quantum and electron transport phenomena
- Topological Materials and Phenomena
- Perovskite Materials and Applications
- Machine Learning in Materials Science
- Surface and Thin Film Phenomena
- Ga2O3 and related materials
- Magnetic properties of thin films
- Diamond and Carbon-based Materials Research
- Nanowire Synthesis and Applications
- MXene and MAX Phase Materials
- Electron and X-Ray Spectroscopy Techniques
- Chalcogenide Semiconductor Thin Films
- BIM and Construction Integration
- Quality and Safety in Healthcare
- Electronic and Structural Properties of Oxides
- Boron and Carbon Nanomaterials Research
- Semiconductor Quantum Structures and Devices
- Semiconductor materials and interfaces
- Advancements in Battery Materials
- Occupational Health and Safety Research
- Molecular Junctions and Nanostructures
- Organic and Molecular Conductors Research
TU Wien
2018-2023
Vorarlberg University of Applied Sciences
2023
The University of Texas at Austin
2021
Single-photon emitters play a key role in present and emerging quantum technologies. Several recent measurements have established monolayer WSe_{2} as promising candidate for reliable single-photon source. The origin underlying microscopic processes remained, however, largely elusive. We multiscale tight-binding simulation the optical spectra of under nonuniform strain presence point defects employing Bethe-Salpeter equation. Strain locally shifts excitonic energy levels into band gap where...
Mechanical strain is a powerful tuning knob for excitons, Coulomb-bound electron-hole complexes dominating optical properties of two-dimensional semiconductors. While the response bright free excitons broadly understood, behaviour dark (long-lived excitations that generally do not couple to light due spin and momentum conservation) or localized related defects remains mostly unexplored. Here, we study these fragile many-body states on pristine suspended WSe
We construct a continuum model of twisted trilayer graphene using {\it ab initio} density-functional-theory calculations, and apply it to address electronic structure. Our accounts for moir\'e variation in site energies, hopping between outside layers within layers. focus on the role mirror symmetry present ABA trilayers with middle layer twist. The is lost intentionally when displacement field applied layers, unintentionally top shifted laterally relative bottom layer. use two band...
We present measurements of quantized conductance in electrostatically induced quantum point contacts bilayer graphene. The application a perpendicular magnetic field leads to an intricate pattern lifted and restored degeneracies with increasing field: at zero the degeneracy one-dimensional subbands is four, because twofold spin valley degeneracy. By switching on field, lifted. Because Berry curvature, states from different valleys split linearly field. In Hall regime fourfold degenerate...
Band nesting occurs when conduction and valence bands are approximately equispaced over regions in the Brillouin zone. In two-dimensional materials, band results singularities of joint density states thus a strongly enhanced optical response at resonant frequencies. We exploit high sensitivity such resonances to small changes structure sensitively probe strain semiconducting transition metal dichalcogenides (TMDs). measure calculate polarization-resolved second harmonic generation (SHG)...
We present an approach for embedding defect structures modeled by density functional theory into large-scale tight-binding simulations. extract local parameters the vicinity of site using Wannier functions. In transition region between bulk lattice and are continuously adjusted to limit far away from defect. This allows accurate high-level treatment orbitals as many ten nearest neighbors while keeping a small number in render overall computational cost reasonable. As example our approach, we...
Two-particle spectroscopy with correlated electron pairs is used to establish the causal link between secondary spectrum, ($\ensuremath{\pi}+\ensuremath{\sigma}$) plasmon peak, and unoccupied band structure of highly oriented pyrolytic graphite. The spectrum resolved respect involved interband transitions clearly exhibits final state effects, in particular due energy gap interlayer resonances along $\mathrm{\ensuremath{\Gamma}}A$ direction. corresponding effects can also be identified...
In twisted van der Waals (vdW) bilayers, intrinsic strain associated with the moiré superlattice and unintentionally introduced uniaxial may be present simultaneously. Both strains are able to lift degeneracy of E2g phonon modes in Raman spectra. Because different rotation symmetry two types strain, corresponding intensity exhibits a distinct polarization dependence. We compare 2.5° MoS2 bilayer, which maximal is anticipated, natural bilayer an intentionally strain. By analyzing frequency...
The moir\'e potential of graphene on hexagonal boron nitride (hBN) generates a supercell sufficiently large as to thread full magnetic flux quantum ${\mathrm{\ensuremath{\Phi}}}_{0}$ for experimentally accessible field strengths. Close rational fractions ${\mathrm{\ensuremath{\Phi}}}_{0}$, $p/q\ifmmode\cdot\else\textperiodcentered\fi{}{\mathrm{\ensuremath{\Phi}}}_{0}$, magnetotranslation invariance is restored giving rise Brown-Zak fermions featuring the same dispersion relation in absence...
Stacking two layers of two-dimensional materials slightly twisted relative to each other causes significant alternations the physical properties resulting bilayer. For graphene, at right twist angle, electronic band structure features a flat Fermi level that gives rise interesting many-body physics such as correlated insulators or superconducting states. Likewise, finite angle modifies phonon structure. A reciprocal space continuum model including lattice reconstruction due relaxation allows...
Smoothly confined graphene quantum dots (GQDs) localize Dirac electrons with conserved spin and valley degrees of freedom. Recent experimental realization such structures using a combination magnetic fields scanning tunneling microscope tip showcased their potential in locally probing adjusting the degree The present work models influence lattice defects on level structure GQDs. We study both adiabatic spacing ``landscape''---orbital splitting splitting---as well as transition dynamics...
Digital solutions for the construction industry are promising to improve energy consumption, tool life cycle, design, productivity, safety, health, and risk management. In this study we assess feasibility of using accelerometer data obtained from a low-power Micro-Electro-Mechanical Systems (MEMS) sensor directly placed on tool, identify screwdriver usage types. We focus performance evaluation several distinct features machine learning (ML) techniques regarding their accuracy model size. To...
The moiré potential of graphene on hexagonal boron nitride (hBN) generates a supercell sufficiently large as to thread full magnetic flux quantum $Φ_0$ for experimentally accessible field strengths. Close rational fractions $Φ_0$, $p/q \cdotΦ_0$, magnetotranslation invariance is restored giving rise Brown-Zak fermions featuring the same dispersion relation in absence field. Employing highly efficient numerical approach we have performed first realistic simulation magnetoconductance 250 nm...