A5039916740- Advanced Condensed Matter Physics
- Physics of Superconductivity and Magnetism
- Magnetic properties of thin films
- Magnetic and transport properties of perovskites and related materials
- Copper-based nanomaterials and applications
- Geomagnetism and Paleomagnetism Studies
- Theoretical and Computational Physics
- Iron-based superconductors research
- Nuclear Physics and Applications
- Geophysical and Geoelectrical Methods
- Magnetic Properties of Alloys
- Medical Imaging Techniques and Applications
- Multiferroics and related materials
- Radiation Therapy and Dosimetry
Delft University of Technology
2023
Institut Laue-Langevin
2018-2020
University of Warwick
2018-2020
Previous observations of metastable magnetic skyrmions have shown that close to the equilibrium pocket state has a short lifetime, and therefore rapid cooling is required generate significant skyrmion population at low temperatures. Here, we report lifetime in Cu$_2$OSeO$_3$ extended by factor 50 with introduction only 2.5% zinc doping, allowing over 50% survive when field-cooling rate just 1 K/min. Our systematic study suggests enhancement due removal spins non-magnetic dopant, which...
We present the results of a muon-spin spectroscopy investigation GaV$_4$S$_{8-y}$Se$_{y}$ with $y=0, 2, 4$ and 8. Zero-field measurements suggest that GaV$_{4}$Se$_{8}$ GaV$_{4}$S$_{8}$ have distinct magnetic ground states, latter material showing an anomalous temperature-dependence local field. It is not possible to evolve state continuously between these two systems, intermediate $y=2$ $4$ materials glassy behaviour at low temperature. The skyrmion lattice (SkL) phase evident in $y=0$ 8...
The bulk helimagnet ${\mathrm{Cu}}_{2}{\mathrm{OSeO}}_{3}$ represents a unique example in the family of B20 cubic helimagnets exhibiting tilted spiral and skyrmion phase at low temperatures when magnetic field is applied along easy $\ensuremath{\langle}001\ensuremath{\rangle}$ crystallographic direction. Here we present systematic study stability ordering these low-temperature states. We focus our attention on temperature dependencies state that observe persisting up to above $T=35...
We present an investigation into the structural and magnetic properties of Zn-substituted ${\mathrm{Cu}}_{2}{\mathrm{OSeO}}_{3}$, a system in which skyrmion lattice (SkL) phase field--temperature diagram was previously seen to split as function increasing Zn concentration. find that splitting SkL is only observed polycrystalline samples reflects occurrence several coexisting phases with different content, each distinguished by behavior. No such multiphase behavior single-crystal samples.
We report small-angle neutron scattering (SANS) measurements of the skyrmion lattice in ${({\mathrm{Cu}}_{0.976}{\mathrm{Zn}}_{0.024})}_{2}{\mathrm{OSeO}}_{3}$ under application electric and magnetic fields. These show an expansion stability region with field. Furthermore, using time-resolved SANS, we observe slow formation skyrmions after or field is applied, which has not been observed pristine ${\mathrm{Cu}}_{2}{\mathrm{OSeO}}_{3}$ crystals. The measured times are dramatically longer than...
Magnetic skyrmions are nano-sized topological spin textures stabilized by a delicate balance of magnetic energy terms. The chemical substitution the underlying crystal structure skyrmion-hosting materials offers route to manipulate these contributions, but also introduces additional effects such as disorder and pinning. While doping have been well studied in B20 metallic Fe$_{1-x}$Co$_x$Si Mn$_{1-x}$Fe$_x$Si, consequences magnetoelectric insulator Cu$_2$OSeO$_3$ not fully explored. In this...
We report spatially resolved small-angle neutron-scattering measurements of the conical and skyrmion states a bulk single crystal nickel-substituted ${\mathrm{Cu}}_{2}{\mathrm{OSeO}}_{3}$, with nominal concentration Ni 14%. observe significant spatial dependence structure these magnetic states, characterized by increased disorder misalignment respect to applied field as we approach edge sample. Remarkably, state is also an extended stability towards lower temperatures. Surprisingly, in same...
We report a small-angle neutron scattering study of the helical and skyrmion lattice order in single-crystal ${\mathrm{Cu}}_{2}{\mathrm{OSeO}}_{3}$ under quasihydrostatic helium gas pressures up to 5 kbar. By using as pressure-transmitting medium (PTM) we ensure pressure application with improved hydrostaticity at cryogenic temperatures compared previous reports where liquid PTMs were used. For 5-kbar He observe modest changes ambient phase diagram; critical temperature ${T}_{c}$ by...
The present paper explores the technical possibility to use classical imaging detectors such as Charge-Coupled Devices (CCD) and Complementary Metal-Oxide Semi- conductor (CMOS) cameras counting at lower rates transits smoothly continuous higher rates. gamma-rejection capabilities well efficiency have been investigated with both an AmBe neutron source in-beam experiments.
The bulk helimagnet Cu2OSeO3 represents a unique example in the family of B20 cubic helimagnets exhibiting tilted spiral and skyrmion phase at low temperatures when magnetic field is applied along easy <001> crystallographic direction. Here we present systematic study stability ordering these temperature states. We focus our attention on dependencies state that observe persisting up to above T =35 K, i.e. higher than reported so far. discuss results frame phenomenological theory introduced...
The lack of inversion symmetry in the crystal lattice magnetic materials gives rise to complex noncollinear spin orders through Dzyaloshinskii-Moriya interaction, resulting new physical phenomena, such as emergent electromagnetism.In archetype cubic chiral magnets a universal phase diagram has been found composed helical spiral, conical and skyrmion phase.The latter appears narrow region diagram, so-called A-phase, just below ordering temperature.Recent SANS magnetization measurements on...