A5057955961- Nuclear Physics and Applications
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Rare-earth and actinide compounds
- Magnetic properties of thin films
- Multiferroics and related materials
- Atomic and Subatomic Physics Research
- Physics of Superconductivity and Magnetism
- Magnetic Properties of Alloys
- Iron-based superconductors research
- Characterization and Applications of Magnetic Nanoparticles
- Nuclear reactor physics and engineering
- High-pressure geophysics and materials
- Radiation Detection and Scintillator Technologies
- Magnetic Properties and Applications
- Iron oxide chemistry and applications
- Theoretical and Computational Physics
- Particle accelerators and beam dynamics
- Electronic and Structural Properties of Oxides
- Ferroelectric and Piezoelectric Materials
- Radiation Therapy and Dosimetry
- Magnetic Properties and Synthesis of Ferrites
- X-ray Diffraction in Crystallography
- Inorganic Fluorides and Related Compounds
- Quantum, superfluid, helium dynamics
Forschungszentrum Jülich
2015-2024
RWTH Aachen University
2019-2024
Jülich Aachen Research Alliance
2014-2024
Heinz Maier-Leibnitz Zentrum
2012-2022
Stadtwerke Jülich (Germany)
2014-2021
Freie Universität Berlin
2021
Technische Universität Braunschweig
2021
European Spallation Source
2020
Grunberger Diabetes Institute
2020
Science and Technology on Surface Physics and Chemistry Laboratory
2020
Grazing incidence small-angle scattering and electron microscopy have been used to show for the first time that nonspherical nanoparticles can assemble into highly ordered body-centered tetragonal mesocrystals. Energy models accounting directionality magnitude of van der Waals dipolar interactions as a function degree truncation nanocubes illustrated importance directional forces formation initial nanocube clusters dominance multibody in dense packed arrays.
The KWS-1 small-angle neutron scattering (SANS) instrument operated by the Jülich Centre for Neutron Science (JCNS) at research reactor FRM II of Heinz Maier-Leibnitz Zentrum in Garching near Munich has been recently upgraded. was updated, from its active collimation apertures to detector cabling. Most parts were installed first time, including a broadband polarizer, large-cross-section radio-frequency spin flipper, chopper and lenses. A custom-designed hexapod sample position allows heavy...
An overview is provided of the 15 neutron beam instruments making up initial instrument suite European Spallation Source (ESS), and being made available to user community. The ESS source consists a high-power accelerator target station, providing unique long-pulse time structure slow neutrons. design considerations behind structure, moderator geometry layout are presented. 15-instrument two small-angle instruments, reflectometers, an imaging beamline, single-crystal diffractometers; one for...
The bosonic analogs of topological insulators have been proposed in numerous theoretical works, but their experimental realization is still very rare, especially for spin systems. Recently, two-dimensional (2D) honeycomb van der Waals ferromagnets emerged as a new platform excitations. Here, via comprehensive inelastic neutron scattering study and analysis the spin-wave excitations, we report magnon CrXTe
By means of polarized small-angle neutron scattering, we have resolved the long-standing challenge determining magnetization distribution in magnetic nanoparticles absolute units. The reduced magnetization, localized non-interacting nanoparticles, indicates strongly particle shape- dependent surface spin canting with a 0.3(1) and 0.5(1) nm thick shell found for ∼9 nanospheres ∼8.5 nanocubes, respectively. Further, macroscopic results not only from canting, but also drastically inside...
The magnetic structure of the Eu${}^{2+}$ moments in superconducting EuFe${}_{2}$(As${}_{1\ensuremath{-}x}$P${}_{x}$)${}_{2}$ sample with $x=0.15$ has been determined using element-specific x-ray resonant scattering. Combining magnetic, thermodynamic, and scattering measurements, we conclude that long-range ferromagnetic order aligned primarily along c axis coexists bulk superconductivity at zero field. At an applied field $\ensuremath{\ge}$0.6 T, still moments, which are polarized...
Abstract Understanding the assembly of nanoparticles into superlattices with well-defined morphology and structure is technologically important but challenging as it requires novel combinations in-situ methods suitable spatial temporal resolution. In this study, we have followed evaporation-induced during drop casting superparamagnetic, oleate-capped γ -Fe 2 O 3 nanospheres dispersed in toluene real time Grazing Incidence Small Angle X-ray Scattering (GISAXS) combination droplet height...
The vacancy distribution of oxygen and its dynamics directly affect the functional response complex oxides their potential applications. Dynamic control composition may provide possibility to deterministically tune physical properties establish a comprehensive understanding structure-property relationship in such systems. Here, an oxygen-vacancy-induced topotactic transition from perovskite brownmillerite vice versa epitaxial La0.7 Sr0.3 MnO3-δ thin films is identified by real-time X-ray...
Antisite disorder is observed to have significant impact on the magnetic properties of double perovskite Y2CoMnO6 which has been recently identified as a multiferroic. A paramagnetic-ferromagnetic phase transition occurs in this material at Tc ≈ 75 K. At 2 K, it displays strong ferromagnetic hysteresis with coercive field Hc 15 kOe. Sharp steps are curves recorded below 8 In temperature range K ≤ T 5 loops anomalous virgin curve lies outside main loop. The field-cooling conditions well rate...
MARIA (magnetism reflectometer with high incident angle) is a world class vertical sample dedicated to the investigation of thin films in fields magnetism, soft matter and biology. The elliptical vertically focusing guide allows one measure small samples typical size 1 × cm very efficiently. double-bounce polarizer situ pumped 3He SEOP (spin-exchange optical pumping) neutron spin filter cell for analysing polarization reflected beam can be moved into seconds. polarized flux amounts 5 107 n...
Antiphase boundaries in iron oxide nanoparticles with oleic acid coating were found to be a major contributor the observed reduction saturation magnetization.
The thermal moderator is the key component in a research neutron source to convert primary neutrons which typically have energies MeV regime into useful for investigations with well below 1 eV. In case of HiCANS as HBS, has be optimized according compact target size and proton pulse lengths at individual stations. Here, details design serving up 12 instruments station its neutronic performance are presented. consists complex aluminium vessel filled light water material containing thin-walled...
We present results of a structural investigation oxygen ordering in 0.1-${\mathrm{cm}}^{3}$ ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6.35}$ single crystal. For the first time nonmagnetic superstructure reflections have been observed by neutron diffraction. From intensities 2 \ensuremath{\surd}2 a\ifmmode\times\else\texttimes\fi{}2 a\ifmmode\times\else\texttimes\fi{}c model is derived. In this structure ``half-filled'' CuO chains alternate with ``quarter-filled'' chains. Only 15%...
The mesostructure of ordered arrays anisotropic nanoparticles is controlled by a combination packing constraints and interparticle interactions, two factors that are strongly dependent on the particle morphology. We have investigated how degree truncation iron oxide nanocubes controls orientation in drop cast mesocrystal arrays. grazing incidence small-angle X-ray scattering scanning electron microscopy shows mesocrystals highly truncated cubic assemble an fcc-type mesostructure, similar to...
A determination of the superconducting (SC) electron pairing symmetry forms basis for establishing a microscopic mechanism superconductivity. For iron pnictide superconductors, ${s}^{\ifmmode\pm\else\textpm\fi{}}$-pairing theory predicts presence sharp neutron spin resonance at an energy below sum hole and SC gap energies ($E\ensuremath{\le}2\ensuremath{\Delta}$) ${T}_{c}$. On other hand, ${s}^{++}$-pairing expects broad excitation enhancement above $2\ensuremath{\Delta}$ Although has been...
We present comprehensive investigations on a pyrochlore antiferromagnet Na${}_{3}$Co(CO${}_{3}$)${}_{2}$Cl. Performed dc magnetization indicates broad maximum at around 4 K. The field dependence of the peak temperature this follows de Almeida--Thouless line, suggesting spin-glass-like phase transition. ac susceptibility measurements determine glassy transition to be 4.5 K and reveal frequency-independent 17 specific heat shows sharp 1.5 hump 5 K, which are attributed long-range magnetic...
The investigations of the interconnection between micro- and macroscopic properties materials hosting noncollinear antiferromagnetic ground states are challenging. These forefront studies crucial for unraveling underlying mechanisms at play, which may prove beneficial in designing cutting edge multifunctional future applications. In this context, Mn5Si3 has regained scientific interest since it displays an unusual complex state, is considered to be origin anomalous transport thermodynamic...
Abstract Topotactic phase transitions induced by changes in the oxygen vacancy concentration can largely alter physical properties of complex oxides, including electronic and magnetic phases, while maintaining structural integrity crystal lattice. An oxygen‐vacancy‐induced topotactic transition from perovskite (PV) to brownmillerite (BM) is achieved epitaxial La 0.6 Sr 0.4 CoO 3−δ (LSCO) thin films. Two novel intermediate states with different content are identified X‐ray diffraction, which...
The JULIC Neutron Platform was set up at the COSY facility in Jülich as a testbed for HBS project. Its center is target station prototype using tantalum and 45 MeV proton beam with maximum power of few watts. Eight extraction ducts allow neutron beams fast, epithermal, thermal cold energy range from moderator-reflector assembly. Reflectometry diffractometry measurements, fast imaging, detector tests moderator/reflector were performed to show technological feasibility components concepts.
To decide whether magnetic fluctuations are present in the high-temperature superconductor YBa2Cu3O7, we carried out a neutron scattering experiment, using 3-dimensional polarization analysis at temperatures between 70 K and 300 K. The total intensity within energy windows - Ω < ℏω for = 12 meV 25 is vanishingly small. Very severe upper bounds could be established, making couplings as source superconductivity YBa2Cu3O7 highly unlikely.
The magnetic 2D to 3D crossover behavior of well-ordered arrays monodomain γ-Fe(2)O(3) spherical nanoparticles with different thicknesses has been investigated by magnetometry and Monte Carlo (MC) simulations. Using the structural information obtained from grazing incidence small-angle X-ray scattering scanning electron microscopy together experimentally determined values for saturation magnetization anisotropy nanoparticles, we show that MC simulations can reproduce thickness-dependent...
We present an exchange bias (EB) effect of variable size in La${}_{0.67}$Sr${}_{0.33}$MnO${}_{3\ensuremath{-}\ensuremath{\delta}}$ single and La${}_{0.67}$Sr${}_{0.33}$MnO${}_{3\ensuremath{-}\ensuremath{\delta}}$/SrTiO${}_{3}$ (LSMO/STO) bilayers grown on STO substrates. Samples have been prepared by pulsed laser deposition (PLD) high-pressure sputter (HSD) oxygen atmosphere at different pressures. Increased out-of-plane lattice parameters the LSMO layers reduced Curie temperatures indicate...
The magnetic-field-induced assembly of magnetic nanoparticles (NPs) provides a unique and flexible strategy in the design fabrication functional nanostructures devices. We have investigated field-induced self-assembly core-shell iron oxide NPs dispersed toluene by means small-angle neutron scattering (SANS). form factor was characterized analyzed using SANS with polarized neutrons. Large-scale aggregates formed above 0.02 T as indicated very-small-angle measurements. A three-dimensional...