A5086409831- Rare-earth and actinide compounds
- Iron-based superconductors research
- Magnetic Properties of Alloys
- Inorganic Chemistry and Materials
- X-ray Diffraction in Crystallography
- Advanced X-ray Imaging Techniques
- Nuclear materials and radiation effects
- Magnetic and transport properties of perovskites and related materials
- Magnetic properties of thin films
- Advanced Condensed Matter Physics
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Electron Microscopy Techniques and Applications
- Crystallization and Solubility Studies
- Microwave Dielectric Ceramics Synthesis
- Shape Memory Alloy Transformations
- Magneto-Optical Properties and Applications
- Physics of Superconductivity and Magnetism
- Advanced Chemical Physics Studies
- Particle Accelerators and Free-Electron Lasers
- Crystal Structures and Properties
- Electronic and Structural Properties of Oxides
- Luminescence Properties of Advanced Materials
- nanoparticles nucleation surface interactions
- Magnetic Properties and Applications
- Crystallography and Radiation Phenomena
European X-Ray Free-Electron Laser
2014-2024
Uppsala University
2022-2024
Lund University
2024
Moscow Engineering Physics Institute
2010-2020
Universität Hamburg
2014-2017
Ryazan State Radio Engineering University
2017
Florida State University
2011-2016
Joint Institute for Nuclear Research
2015
Kurchatov Institute
2010-2014
Lomonosov Moscow State University
2010-2013
We demonstrate that the action of physical pressure, chemical compression, or aliovalent substitution in ACo2As2 (A = Eu and Ca) has a general consequence causing these antiferromagnetic materials to become ferromagnets. In all cases, mixed valence triggered at electropositive A site results increase Co 3d density states Fermi level. Remarkably, dramatic alteration magnetic behavior from very minor (<0.15 electron) change population orbitals. The state observed high-pressure (HP) form...
The SASE3 soft X-ray beamline at the European XFEL has been designed and built to provide experiments with a pink or monochromatic beam in photon energy range 250–3000 eV. Here, focus is operation of beamline, design performance grating monochromator are reported. unique capability free-electron laser source produce short femtosecond pulses high degree coherence challenges by demanding control both temporal resolution. aim transport close transform-limited poses very demands on optics...
The complex electronic structure of metallic ferromagnets is determined by a balance between exchange interaction, electron hopping leading to band formation, and local Coulomb repulsion. By combining high energy temporal resolution in femtosecond time-resolved X-ray absorption spectroscopy with ab initio time-dependent density functional theory we analyze the fcc Ni on time scale these interactions pump-probe experiment. We distinguish transient broadening shifts spectra, which demonstrate...
Magnetic nanoparticles such as FePt in the L1 0 phase are bedrock of our current data storage technology. As grains become smaller to keep up with technological demands, superparamagnetic limit calls for materials higher magnetocrystalline anisotropy. This, turn, reduces magnetic exchange length just a few nanometers, enabling structures be induced within nanoparticles. Here, we describe existence spin-wave solitons, dynamic localized bound states excitations, We show time-resolved x-ray...
Femtosecond transient soft X-ray absorption spectroscopy (XAS) is a very promising technique that can be employed at free-electron lasers (FELs) to investigate out-of-equilibrium dynamics for material and energy research. Here, dedicated setup X-rays available the Spectroscopy Coherent Scattering (SCS) instrument European Free-Electron Laser (European XFEL) presented. It consists of beam-splitting off-axis zone plate (BOZ) used in transmission create three copies incoming beam, which are...
Magnetic properties of itinerant magnets depend on peculiarities their electronic band structure. Introduction Eu into PrCo2P2 pushes the material from antiferromagnetism to ferromagnetism. The change is due a strong chemical compression that "squeezes out" electrons localized 4f levels delocalized Co 3d subband.
Four rare-earth cobalt arsenides, RCo2As2 (R = La, Ce, Pr, Nd), were obtained by reactions of constituent elements in molten Bi. The use Bi flux also allowed the growth representative single crystals. All compounds are isostructural and belong to ThCr2Si2 type (space group I4/mmm). formation Co vacancies is observed all structures, while structures La- Ce-containing show incorporation minor defects next R crystallographic site. Correspondingly, general formula these materials can be written...
Identifying the microscopic nature of non-equilibrium energy transfer mechanisms among electronic, spin, and lattice degrees freedom is central to understanding ultrafast phenomena such as manipulating magnetism on femtosecond timescale. Here, we use time- angle-resolved photoemission spectroscopy go beyond often-used ensemble-averaged view dynamics in terms quasiparticle temperature evolutions. We show for ferromagnetic Ni that electron spin display pronounced variations with momentum,...
In mixed-valence or heavy-fermion systems, the hybridization between local $f$ orbitals and conduction band states can cause suppression of long-range magnetic order, which competes with strong spin fluctuations. Ce- Yb-based systems have been found to exhibit fascinating physical properties (heavy-fermion superconductivity, non-Fermi-liquid states, etc.) when tuned vicinity quantum critical points by use various external control parameters (temperature, field, chemical composition)....
We report the inelastic neutron scattering study of spin dynamics in EuCu 2 (Si x Ge 1-x ) (x = 1, 0.9, 0.75, 0.6), performed a wide temperature range.At 1 magnetic excitation spectrum was found to be represented by double-peak structure well below energy range Eu 3+ spin-orbit (SO) 7 F 0 → , so that at least high-energy spectral component can assigned renormalized SO transition.Change valence towards 2+ with increased and/or concentration results further renormalization (lowering energy)...
Wide-band-gap insulators such as NiO offer the exciting prospect of coherently manipulating electronic correlations with strong optical fields. Contrary to metals where rapid dephasing excitation via processes occurs, sub-gap in charge-transfer has been shown couple low-energy bosonic excitations. However, it is currently unknown if dressing field composed phonons or magnons. Here we use prototypical insulator demonstrate that 1.5 eV leads a renormalised band-gap combination significant...
The advent of X-ray free-electron lasers (XFELs) has revolutionized fundamental science, from atomic to condensed matter physics, chemistry biology, giving researchers access X-rays with unprecedented brightness, coherence and pulse duration. All XFEL facilities built until recently provided pulses at a relatively low repetition rate, limited data statistics. Here, results the first megahertz-repetition-rate scattering experiments Spectroscopy Coherent Scattering (SCS) instrument European...
A real-time and accurate characterization of the X-ray beam size is essential to enable a large variety different experiments at free-electron laser facilities. Typically, ablative imprints are employed determine shape µm-focused beams. The high accuracy this state-of-the-art method comes expense time required perform an ex-situ image analysis. In contrast, diffraction curved grating with suitably varying period orientation forms magnified beam, which can be recorded by 2D pixelated detector...
A change of orbital state alters the coupling between ions and their surroundings drastically. Orbital excitations are hence key to understand control interaction ions. Rare-earth elements with strong magneto-crystalline anisotropy (MCA) important ingredients for magnetic devices. Thus, localized 4
The parent compound <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>BaBiO</a:mi><a:mn>3</a:mn></a:msub></a:math> of bismuthate high-temperature superconductors (HTSCs) <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:mi>BaBi</b:mi><b:mrow><b:mo>(</b:mo><b:mi>Pb</b:mi><b:mo>)</b:mo></b:mrow><b:msub><b:mi mathvariant="normal">O</b:mi><b:mn>3</b:mn></b:msub></b:mrow></b:math> and <d:math...
The cerium effective valence was investigated by means of CeL3-XANES spectroscopy in some intermediate Ce-based systems with different magnetic ordering mechanisms: CeNi doped Nd, Pr and Gd the temperature range 5–300 K, Ce3Fe17–xMnx intermetallics. dependences obtained are considered within frames generally accepted mechanisms rare-earth ions states. Possible correlations between properties compounds also noted.