A5101711478- Magnetic properties of thin films
- Rare-earth and actinide compounds
- Magnetic and transport properties of perovskites and related materials
- Physics of Superconductivity and Magnetism
- Magnetic Properties of Alloys
- High-pressure geophysics and materials
- Heusler alloys: electronic and magnetic properties
- Iron-based superconductors research
- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Advanced NMR Techniques and Applications
- Magnetic Properties and Applications
- Advanced MRI Techniques and Applications
- Advanced Materials Characterization Techniques
- Quantum and electron transport phenomena
- Numerical methods in inverse problems
- Advanced Condensed Matter Physics
- Crystallization and Solubility Studies
- Intermetallics and Advanced Alloy Properties
- Metallurgical and Alloy Processes
- X-ray Diffraction in Crystallography
- NMR spectroscopy and applications
- Advanced Optimization Algorithms Research
- Sparse and Compressive Sensing Techniques
- Advanced Welding Techniques Analysis
University Medical Centre Mannheim
2016-2022
Heidelberg University
2016-2022
University Hospital Heidelberg
2016-2022
Johannes Kepler University of Linz
2022
Technical University of Munich
2010-2021
Federal Institute For Materials Research and Testing
2012
University of Cologne
2009
Heinz Maier-Leibnitz Zentrum
2009
Skyrmions represent topologically stable field configurations with particle-like properties. We used neutron scattering to observe the spontaneous formation of a two-dimensional lattice skyrmion lines, type magnetic vortex, in chiral itinerant-electron magnet MnSi. The stabilizes at border between paramagnetism and long-range helimagnetic order perpendicular small applied regardless direction relative atomic lattice. Our study experimentally establishes materials lacking inversion symmetry...
Recent small angle neutron scattering suggests that the spin structure in A phase of MnSi is a so-called triple-Q state, i.e., superposition three helices under 120 degrees. Model calculations indicate this fact lattice Skyrmions, topologically stable knots structure. We report distinct additional contribution to Hall effect temperature and magnetic field range proposed Skyrmion lattice, where such neither seen nor expected for normal helical state. Our measurements constitute direct...
Spin manipulation using electric currents is one of the most promising directions in field spintronics. We used neutron scattering to observe influence an current on magnetic structure a bulk material. In skyrmion lattice manganese silicon, where spins form vortices similar vortex type II superconductors, we rotation diffraction pattern response that are over five orders magnitude smaller than those typically applied experimental studies current-driven magnetization dynamics nanostructures....
We report a comprehensive small angle neutron scattering study (SANS) of the magnetic phase diagram doped semiconductor Fe_{1-x}Co_{x}Si for x=0.2 and 0.25. For field parallel to beam we observe six-fold intensity pattern under field-cooling, which identifies A-phase as skyrmion lattice. The regime lattice is highly hysteretic extents over wide temperature range, consistent with site disorder Fe Co atoms. Our second material after MnSi in forms establishes that lattices may also occur...
We report the magnetization, ac susceptibility, and specific heat of optically float-zoned single crystals ${\text{Mn}}_{1\ensuremath{-}x}{\text{Fe}}_{x}\text{Si}$ ${\text{Mn}}_{1\ensuremath{-}x}{\text{Co}}_{x}\text{Si}$ for temperatures down to $\ensuremath{\sim}2\text{ }\text{K}$ magnetic fields up 9 T. The suppression helimagnetic transition temperature ${T}_{1}$ above a critical composition ${x}_{1}$, as seen in heat, suggests existence quantum phase at ${x}_{1}$. A Vollhardt invariance...
High pressure studies in MnSi suggest the existence of a non-Fermi liquid state without quantum criticality. The observation partial magnetic order small pocket versus temperature phase diagram has additionally inspired several proposals complex spin textures chiral magnets. We used neutron scattering to observe formation two-dimensional lattice skyrmion lines, type vortices, under applied fields metallic and semiconducting B20 compounds. In strongly disordered systems is hysteretic extends...
We report small angle neutron scattering of the Skyrmion lattice in MnSi using an experimental setup that minimizes effects demagnetizing fields and double scattering. Under these conditions, displays resolution-limited Gaussian rocking peaks correspond to a magnetic correlation length excess several hundred micrometers. This is consistent with exceptionally well-defined long-range order. further establish existence higher-order scattering, discriminating parasitic Renninger scans. The field...
We report the design of an optical floating-zone furnace for single-crystal growth under ultra-high vacuum (UHV) compatible conditions. The system is based on a commercial image furnace, which has been refurbished to be all-metal sealed. Major changes concern use UHV rotary feedthroughs and bespoke quartz-metal seals with metal-O-rings at lamp stage. As consequence, procedure assembling crystal changed completely. Bespoke heating jackets permit bake system. For compounds elevated vapor...
We report a study of the spin moment in single crystal Nb${}_{(1\ensuremath{-}y)}$Fe${}_{(2+y)}$ with $y=0.015$ using spin-dependent Compton scattering conjunction ab initio electronic structure calculations. From experiment, we find that total is $0.245\ifmmode\pm\else\textpm\fi{}0.004{\ensuremath{\mu}}_{B}$. Comparison measured density theoretical results from linearized muffin-tin orbital calculations determines there to be ferrimagnetic arrangement Fe moments, 2$a$ site aligned...
We have investigated single crystals and polycrystals from the series ${\mathrm{Nb}}_{1\ensuremath{-}y}{\mathrm{Fe}}_{2+y}, \ensuremath{-}0.004\ensuremath{\le}y\ensuremath{\le}0.018$, by electron spin resonance, muon relaxation, M\"ossbauer spectroscopy. Our data establish that at lowest temperatures all samples exhibit bulk magnetic order. Slight Fe excess induces low-moment ferromagnetism, consistent with magnetometry, while Nb-rich stoichiometric ${\mathrm{NbFe}}_{2}$ display density wave...
The strongly doped semiconductor Fe1−xCoxSi displays a dome of helimagnetic order for 0.05 ≤ x 0.7. We report small angle neutron scattering the magnetic structure in skyrmion lattice phase = 0.2 and field parallel to crystallographic (100) direction. observe twelve equally spaced maxima intensity on ring, with an underlying six-fold symmetry two sets six spots. distribution suggests formation degenerate domain populations respect four-fold directions plane.
The Hall effect of the dilution series Nb${}_{1\ensuremath{-}y}$Fe${}_{2+y}$ has been studied on selected samples spanning ferromagnetic (FM) and spin-density-wave (SDW) ground states, including a sample in vicinity quantum critical point. Ordinary anomalous contributions are observed, with positive ordinary for all single crystals dominating at high temperatures. Consistent analysis contribution is possible iron-rich Nb${}_{0.985}$Fe${}_{2.015}$ state SDW elevated temperatures...
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...
In this paper we show a first approach to the three dimensional reconstruction of spatially resolved neutron depolarization data. We will measurements with position sensitive CCD detector on longitudinal polarization analysis setup using 3He polarizers and analyzers installed at radiography beamline ANTARES FRM II, Munich. A tomographic data acquired an inhomogeneous Pd1−xNix sample shows that method is powerful tool identify regions different magnetic properties inside sample.
Systems lacking inversion symmetry, such as selected three-dimensional compounds, multilayers and surfaces support Dzyaloshinsky-Moriya (DM) spin-orbit interactions. In recent years DM interactions have attracted great interest, because they may stabilize magnetic structures with a unique chirality non-trivial topology. The inherent coupling between the various properties provided by is potentially relevant for variety of applications including, instance, multiferroic spintronic devices....
The interaction of the magnetic moment neutron with fields provides a powerful probe for spatially resolved magnetisation measurements in materials. We have tested periscope as new type polarizer providing beams high polarization and low divergence. observed inhomogeneity beam caused by waviness glass substrates was quantified means Monte-Carlo simulations using software package McStas. results show that homogeneity can be produced if is reduced to below 1.0·10−5 rad. Finally, it shown...
We report the design of a radio-frequency induction-heated rod casting furnace that permits preparation polycrystalline ingots intermetallic compounds under ultra-high vacuum compatible conditions. The central part system is bespoke water-cooled Hukin crucible supporting mold. Depending on choice mold, typical rods have diameter between 6 mm and 10 length up to 90 mm, suitable for single-crystal growth by means float-zoning. setup all-metal sealed may be baked out. find resulting represents...
The aim of this study was to observe the effects strophanthin induced inhibition Na-/K-ATPase in liver cells using a magnetic resonance (MR) compatible bioreactor. A microcavity array with high density three-dimensional cell culture served as functional imaging (MRI) phantom for sodium multi quantum (MQ) spectroscopy. Direct contrast enhanced (DCE) MRI revealed homogenous distribution biochemical substances inside NMR experiments advanced bioreactors have advantages respect having full...
The investigation of fragile and potentially inhomogeneous forms ferromagnetic order under extreme conditions, such as low temperatures high pressures, is central interest for areas geophysics, correlated electron systems, well the optimization materials synthesis applications where particular material properties are required. We report neutron depolarization imaging measurements on weak ferromagnet Ni3Al pressures up to 10 kbar using a Cu:Be clamp cell. Using polychromatic beam with...
Abstract We examine the low temperature states of two transition metal compounds: (i) NbFe 2 is poised on threshold ferromagnetism and can be pushed into a spin‐aligned state at by modifying composition slightly. Stoichiometric has been reported as rare example low‐temperature spin density wave order in d‐metal system. have used pressure, field tuning to phase diagram . Near quantum critical point, we find distinct non‐Fermi liquid forms resistivity heat capacity, whereas observe strong,...