A5004553096- Machine Learning in Materials Science
- Advanced Electron Microscopy Techniques and Applications
- Electron and X-Ray Spectroscopy Techniques
- Chalcogenide Semiconductor Thin Films
- Magnetic properties of thin films
- Inorganic Chemistry and Materials
- Advanced Chemical Physics Studies
- Graphene research and applications
- Electronic and Structural Properties of Oxides
- Advanced X-ray Imaging Techniques
- Diamond and Carbon-based Materials Research
- Rare-earth and actinide compounds
- Calibration and Measurement Techniques
- Atomic and Subatomic Physics Research
- Semiconductor materials and devices
- Iron-based superconductors research
- Cold Atom Physics and Bose-Einstein Condensates
- Scientific Computing and Data Management
- Advanced Materials Characterization Techniques
- Magnetic Properties of Alloys
- Physics of Superconductivity and Magnetism
- Atomic and Molecular Physics
- Advanced Condensed Matter Physics
- Advancements in Photolithography Techniques
- Multiferroics and related materials
Aarhus University
2023-2024
Johannes Gutenberg University Mainz
2018-2023
University of Stuttgart
2018
Max Planck Institute for Solid State Research
2018
University of Siena
2017
Time-resolved photoemission with ultrafast pump and probe pulses is an emerging technique wide application potential. Real-time recording of nonequilibrium electronic processes, transient states in chemical reactions, or the interplay structural dynamics offers fascinating opportunities for future research. Combining valence-band core-level spectroscopy photoelectron diffraction electronic, chemical, analyses requires few 10 fs soft X-ray some meV spectral resolution, which are currently...
Time-resolved soft-x-ray photoemission spectroscopy is used to simultaneously measure the ultrafast dynamics of core-level spectral functions and excited states upon excitation excitons in WSe_{2}. We present a many-body approximation for Green's function, which excellently describes transient core-hole function. The relative excited-state signal core levels clearly show delayed renormalization due screening by quasifree carriers resulting from an excitonic Mott transition. These findings...
Femtosecond light-induced phase transitions between different macroscopic orders provide the possibility to tune functional properties of condensed matter on ultrafast timescales. In first-order transitions, transient non-equilibrium phases and inherent coexistence often preclude non-ambiguous detection transition precursors their temporal onset. Here, we present a study combining time-resolved photoelectron spectroscopy ab-initio electron dynamics calculations elucidating subpicosecond...
Abstract Angle-resolved photoemission spectroscopy (ARPES) is a powerful experimental technique to determine the electronic structure of solids. Advances in light sources for ARPES experiments are currently leading vast increase data acquisition rates and quantity. On other hand, access time most advanced instruments remains strictly limited, calling fast, effective, on-the-fly analysis tools exploit this time. In response need, we introduce ARPESNet, versatile autoencoder network that...
We observe the excitation of collective modes in THz range driven by recently discovered N\'{e}el spin-orbit torques (NSOT) metallic antiferromagnet Mn$_{2}$Au. Temperature dependent spectroscopy reveals a strong absorption mode centered near 1 THz, which upon heating from 4 K to 450 softens and looses intensity. Comparison with estimated eigenmode frequencies implies that observed is an in-plane antiferromagnetic resonance (AFMR) mode. The AFMR strength exceeds those found insulators,...
The performance of time-resolved photoemission experiments at fs-pulsed photon sources is ultimately limited by the e–e Coulomb interaction, downgrading energy and momentum resolution. Here, we present an approach to effectively suppress space-charge artifacts in microscopes microscopes. A retarding electrostatic field generated a special objective lens repels slow electrons, retaining k-image fast photoelectrons. suppression effects scales with ratio photoelectron velocities electrons....
Angle-resolved photoemission spectroscopy (ARPES) is a technique used to map the occupied electronic structure of solids. Recent progress in X-ray focusing optics has led development ARPES into microscopic tool, permitting be spatially mapped across surface sample. This comes at expense time-consuming scanning process cover not only three-dimensional energy-momentum ($E, k_z, k_y$) space but also two-dimensional area. Here, we implement protocol autonomously search both $\mathbf{k}$- and...
The coupling of real and momentum space is utilized to tailor electronic properties the collinear metallic antiferromagnet Mn2Au by aligning Néel vector indicating direction staggered magnetization. Pulsed magnetic fields 60 T were used orient sublattice magnetizations capped epitaxial Mn2Au(001) thin films perpendicular applied field a spin-flop transition. structure its corresponding changes investigated angular-resolved photoemission spectroscopy with photon energies in...
Abstract Characterization of the electronic band structure solid state materials is routinely performed using photoemission spectroscopy. Recent advancements in short-wavelength light sources and electron detectors give rise to multidimensional spectroscopy, allowing parallel measurements spectral function simultaneously energy, two momentum components additional physical parameters with single-event detection capability. Efficient processing photoelectron event streams at a rate up tens...
We show that the presence of a transiently excited hot electron gas in graphene leads to substantial broadening C $1s$ line probed by time-resolved x-ray photoemission spectroscopy. The is found be caused an exchange energy and momentum between photoemitted core gas, rather than vibrational excitations. This interpretation supported quantitative line-shape analysis accounts for electrons. Fitting spectra this model directly yields electronic temperature system, good agreement with values...
Abstract High-resolution full-field imaging of ( k x , y ) photoelectron distributions -resolution 0.03 Å −1 angular resolution 0.03° at 6.7 keV) in a large field view (up to 16 dia.) allows observe fine details Kikuchi-type diffractograms. Alongside with the element specificity via core-level spectra, this method opens new avenue structural analysis using hard x-ray diffraction (hXPD). Here we present theoretical study emitter-site by simulating hXPD patterns for arbitrary positions emitter...
Angle-resolved photoemission spectroscopy (ARPES) is a technique used to map the occupied electronic structure of solids. Recent progress in x-ray focusing optics has led development ARPES into microscopic tool, permitting be spatially mapped across surface sample. This comes at expense time-consuming scanning process cover not only three-dimensional energy-momentum (E, kx, ky) space but also two-dimensional area. Here, we implement protocol autonomously search both k- and real-space order...
How can we efficiently and scalably cluster high-dimensional data? The k -means algorithm clusters data by iteratively reducing intra-cluster Euclidean distances until convergence. While it finds applications from recommendation engines to image segmentation, its application is hindered the need repeatedly compute among points centroids. In this paper, propose Marigold ( for data), a scalable clustering in high dimensions. prunes distance calculations means of (i) tight distance-bounding...
X-ray photoelectron diffraction is a powerful tool for determining the structure of clean and adsorbate-covered surfaces. Extending technique into ultrafast time domain will open door to studies as diverse direct determination electron-phonon coupling strength in solids mapping atomic motion surface chemical reactions. Here we demonstrate time-resolved using ultrashort soft pulses from free electron laser FLASH. We collect Se 3d patterns over wide angular range optically excited Bi$_2$Se$_3$...
Abstract Controlled atomic desorption from organic Poly-DiMethylSiloxane coating is demonstrated for improving the loading efficiency of 209,210 Fr magneto-optical traps. A three times increase in cold atoms population obtained with contact-less pulsed light-induced desorption, applied to different isotopes, either bosonic or fermionic, Francium. six 210 a mechanism based on direct charge transfer triboelectric probe adatom-organic complex. Our findings provide new insight microscopic...
Abstract The heavy-fermion behavior in intermetallic compounds manifests itself a quenching of local magnetic moments by developing Kondo spin-singlet many-body states combined with drastic increase the effective mass conduction electrons, which occurs below lattice temperature T K . This is caused interactions between strongly localized 4 f electrons and itinerant electrons. A controversially discussed question this context how electronic contribute to Fermi surface upon changing...
Angle-resolved photoemission spectroscopy (ARPES) is a powerful experimental technique to determine the electronic structure of solids. Advances in light sources for ARPES experiments are currently leading vast increase data acquisition rates and quantity. On other hand, access time most advanced instruments remains strictly limited, calling fast, effective, on-the-fly analysis tools exploit this time. In response need, we introduce ARPESNet, versatile autoencoder network that efficiently...
We report on the direct experimental observation of 7pP23/2→7dD2 optical transitions in 209 and 210 francium isotopes. By continuously monitoring fluorescence emitted by isotopes collected a magneto-optical trap (MOT), electric dipole 7pP23/2→7dD25/2 Fr209, not yet experimentally observed, 7pP23/2→7dD25/2, Fr210 were detected as sub-Doppler depletion dips cold atom population. This approach allowed unambiguous identification excited state hyperfine structures, even absence large stable...
The excitonic insulator (EI) is an intriguing phase of condensed excitons undergoing a Bose-Einstein-Condensation (BEC)-type transition. A prominent candidate has been identified in Ta<sub>2</sub>NiSe<sub>5</sub>. Ultrafast spectroscopy allows tracing the coherent response EI condensate directly time domain. Probing collective electronic we can identify fingerprints for Higgs-amplitude equivalent mode condensate. In addition find peculiar coupling to low frequency phonon mode. We will...
In heavy fermions the relaxation dynamics of photoexcited carriers has been found to be governed by low energy indirect gap, E$_{g}$, resulting from hybridization between localized moments and conduction band electrons. Here, carrier in a prototype Kondo insulator YbB${}_{12}$ is studied over large range temperatures three orders magnitude. We utilize intrinsic non-linearity quantitatively determine microscopic parameters, such as electron-hole recombination rate. The extracted value reveals...