A5062234703- Magnetic properties of thin films
- Magnetic Properties and Applications
- Nuclear Physics and Applications
- Theoretical and Computational Physics
- Advanced Condensed Matter Physics
- Magnetic Properties of Alloys
- Magnetic and transport properties of perovskites and related materials
- Multiferroics and related materials
- Atomic and Subatomic Physics Research
- Physics of Superconductivity and Magnetism
- Metallic Glasses and Amorphous Alloys
- Advanced Materials Characterization Techniques
- Rare-earth and actinide compounds
- ZnO doping and properties
- High-pressure geophysics and materials
- Inorganic Chemistry and Materials
- Medical Imaging Techniques and Applications
- Quantum, superfluid, helium dynamics
- Radiation Detection and Scintillator Technologies
- Machine Learning in Materials Science
- Boron and Carbon Nanomaterials Research
- Advanced materials and composites
- Metallurgical and Alloy Processes
Austin Health
2024
Technical University of Munich
2012-2022
University of Bremen
2017
Heinz Maier-Leibnitz Zentrum
2012-2015
Skyrmion crystals are regular arrangements of magnetic whirls that exist in a wide range chiral magnets. Because their topology, they cannot be created or destroyed by smooth rearrangements the direction local magnetization. Using force microscopy, we tracked destruction skyrmion lattice on surface bulk crystal Fe(1-x)Co(x)Si (x = 0.5). Our study revealed skyrmions vanish coalescence, forming elongated structures. Numerical simulations showed changes topology controlled singular point...
We report a long-wavelength helimagnetic superstructure in bulk samples of the ferrimagnetic insulator Cu2OSeO3. The magnetic phase diagram associated with modulation inferred from small angle neutron scattering and magnetisation measurements includes skyrmion lattice is strongly reminiscent MnSi, FeGe Fe1-xCoxSi, i.e., binary isostructural siblings Cu2OSeO3 that order helimagnetically. temperature dependence specific heat characteristic nearly critical spin fluctuations at transition. This...
Entropic effects counteract the topological protection of magnetic skyrmions, leading to faster decay rates than expected.
We report comprehensive small angle neutron scattering measurements complemented by ac susceptibility data of the helical order, conical phase, and Skyrmion lattice phase (SLP) in MnSi under uniaxial pressures. For all crystallographic orientations pressure favors for which a spatial modulation magnetization is closest to axis. Uniaxial pressures as low 1 kbar applied perpendicular magnetic field axis enhance substantially, whereas suppressed parallel field. Taken together we present...
The Dzyaloshinskii-Moriya interaction in the cubic chiral magnet MnSi stabilizes a magnetic helix - periodic one-dimensional modulation of magnetization. orientation this is determined by weak magnetocrystalline anisotropies, but it can be reoriented applying field. Here, authors have studied reorientation process means small-angle neutron scattering and susceptibility measurements. Their results are excellent agreement with predictions an effective mean-field theory taking into account...
Precision measurements of the magnetization and ac susceptibility Cu$_2$0SeO$_3$ are reported for magnetic fields along different crystallographic directions, focussing on border between conical field-polarized state a field $\langle 100 \rangle$ axis, complemented by selected specific heat data. Clear signatures emergence second skyrmion phase tilted observed, as recently identified means small-angle neutron scattering. The low-temperature displays strongly hysteretic boundaries, but no...
We report an experimental study of the emergence non-trivial topological winding and long-range order across paramagnetic to skyrmion lattice transition in metal helimagnet MnSi. Combining measurements susceptibility with small angle neutron scattering, resonance spin echo spectroscopy all-electrical microwave spectroscopy, we find evidence textures state exceeding $10^3$\AA lifetimes above several 10$^{-9}$s. Our findings establish that MnSi is well-described by Landau soft-mode mechanism...
We report a comprehensive small-angle neutron scattering (SANS) study of magnetic correlations in ${\mathrm{Mn}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{x}\mathrm{Si}$ at zero field. To delineate changes magnetocrystalline anisotropies (MCAs) from effects due to defects and disorder, we recorded complementary susceptibility high-resolution specific heat data investigated selected compositions ${\mathrm{Mn}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}\mathrm{Si}$. For all systems studied, the helimagnetic...
We report the development of a versatile module that permits fast and reliable use focussing neutron guides under varying scattering angles. A simple procedure for setting up is illustrated by typical intensity patterns to highlight operational aspects as well parasitic artefacts. Combining high-precision alignment table with separate housings on kinematic mounts, change-over between different characteristics requires no readjustments experimental setup. Exploiting substantial gain factors,...
Magnetic small-angle neutron scattering (SANS) is ideally suited to providing direct reciprocal-space information on long-wavelength magnetic modulations, such as helicoids, solitons, merons or skyrmions. SANS of structures in thin films micro-structured bulk materials strongly limited by the tiny volume vis a prohibitively high background substrate and support structures. Considering near-surface just above critical angle reflection, where unwanted signal contributions due become very...
The availability of large high-quality single crystals is an important prerequisite for many studies in solid-state research. optical floating-zone technique elegant method to grow such crystals, offering potential prepare samples that may be hardly accessible with other techniques. As elaborated this report, examples include intentional compositional gradients, deliberate off-stoichiometry, or complex metallurgy. For the cubic chiral magnets Mn$_{1-x}$Fe$_{x}$Si and Fe$_{1-x}$Co$_{x}$Si, we...
In the neutron resonance spin echo method information about sample dynamics is encoded in beam polarization measured analyzer-detector unit. Thus, not applicable for systems and environments, which depolarize strongly. To over come this draw back a analyzer directly before position may be installed to perform MIEZE-I experiments. We compared performance of transmission polarizer solid-state bender at spectrometer RESEDA by Monte Carlo simulations. It turned out, that as well intensity...
We report grazing incidence small angle neutron scattering (GISANS) and complementary off-specular reflectometry (OSR) of the magnetic order in a single-crystalline epitaxial MnSi film on Si(111) thick limit. Providing means direct reciprocal space mapping, GISANS OSR reveal modulation perpendicular to films under fields parallel film, where additional polarized (PNR) magnetization measurements are excellent agreement with literature. Regardless field orientation, our data does not suggest...
Kinetic small-angle neutron scattering provides access to the microscopic properties of mesoscale systems under slow, periodic perturbations. By interlocking phases pulse, sample modulation and detector signal, time-involved experiments (TISANE) allow one exploit velocity spread record data without major sacrifice in intensity at timescales down microseconds. This article reviews optimization strategies TISANE that arise from specific aspects process acquisition analysis starting basic...
The antiferromagnetic ordering of chromium has long been known for its peculiar physical properties. One them is the observation weak first-order character N'eel transition that explained by lack a stable fixed point Bak and Mukamel. Barak et al. predicted lowering symmetry order parameter application uniaxial pressure along [110] direction changes to second-order. In previous experiment Fawcett al., irreversible broadening Néel was already observed between 160 bar 300 bar, which could,...
Magnetic small-angle neutron scattering (SANS) is ideally suited to provide direct, reciprocal-space information of long-wavelength magnetic modulations, such as helicoids, solitons, merons, or skyrmions. SANS structures in thin films micro-structured bulk materials strongly limited by the tiny volume vis a prohibitively large background substrate and support structures. Considering near-surface closely above critical angle reflection, where unwanted signal contributions due becomes very...