A5079485663- Magnetic properties of thin films
- Advanced X-ray Imaging Techniques
- Advanced Electron Microscopy Techniques and Applications
- Crystallography and Radiation Phenomena
- Magnetic Properties and Applications
- Magnetic Properties of Alloys
- Terahertz technology and applications
- Metallic Glasses and Amorphous Alloys
- Particle Accelerators and Free-Electron Lasers
- X-ray Spectroscopy and Fluorescence Analysis
- Material Dynamics and Properties
- Quantum and electron transport phenomena
- Quantum optics and atomic interactions
- Advanced Fiber Laser Technologies
- Physics of Superconductivity and Magnetism
- Geomagnetism and Paleomagnetism Studies
- Copper Interconnects and Reliability
- Geological and Geochemical Analysis
- Surface Roughness and Optical Measurements
- Atomic and Subatomic Physics Research
- Magneto-Optical Properties and Applications
- Mechanical and Optical Resonators
- Spectroscopy Techniques in Biomedical and Chemical Research
- Magnetic and transport properties of perovskites and related materials
- Optical Coatings and Gratings
Université de Strasbourg
2022-2025
Centre National de la Recherche Scientifique
2024-2025
Institut de Physique et Chimie des Matériaux de Strasbourg
2024-2025
Sorbonne Université
2024
Deutsches Elektronen-Synchrotron DESY
2019-2024
University of Augsburg
2017
Femtosecond laser pulses can be used to induce ultrafast changes of the magnetization in magnetic materials. Several microscopic mechanisms have been proposed explain these observations, including transport ultrashort spin-polarized hot-electrons (SPHE). However, currently such spin currents are only poorly characterized due measurement requirements for element and time resolution. Here, using time- element-resolved X-ray circular dichroism alongside atomistic spin-dynamics simulations, we...
The controlled manipulation of spins on ultrashort timescales is among the most promising solutions for novel high-speed and low-power-consumption spintronic magnetic recording applications. To do so, terahertz (THz) light pulses can be used to drive coherent magnetization dynamics in ferromagnetic thin films. We were able resolve these nanoscale employing THz-pump x-ray resonant scattering from labyrinth-type domain network a Co/Pt multilayer with perpendicular anisotropy. Our results...
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...
We explore the impact of optical excitation using two interfering ultrashort pulses on ultrafast magnetization dynamics. Our investigation focuses Pt/Co/Pt multilayers and TbCo alloy samples, employing a dual pump approach. observe significant variations in dynamics suppression subsequent recovery when triggered with same polarization---essentially meeting conditions for interference. Conversely, cross-polarized beams exhibit expected similarity to that single pulse. Delving into underlying...
We present a systematic 2D spatial-coherence analysis of the soft-X-ray beamline P04 at PETRA III for various configurations. The influence two different beam-defining apertures on spatial coherence properties beam is discussed and optimal conditions coherence-based experiments are found. A significant degradation in vertical direction has been measured sources this identified discussed. Fourier-analysis method, which gives fast simple access to function X-ray beam, used experiment. Here, we...
Abstract The availability of sub 100 fs short and highly intense free-electron laser (FEL) pulses allows for new insights in laser-induced ultrafast demagnetization (LID) ferromagnetic thin films on nanometer length scales. We designed a pair in-vacuum Helmholtz coils, providing pulsed magnetic fields up to µ 0 H z = ±45 mT, time-resolved experiments at FEL sources transmission geometry. report the implementation coils an optical-pump–resonant-magnetic-scattering (tr-XRMS) experiment FERMI...
The ability of pulsed nature synchrotron radiation opens up the possibility studying microsecond dynamics in complex materials via speckle-based techniques. Here, we present study measuring a colloidal system by combining single and multiple X-ray pulses storage ring. In addition, apply speckle correlation techniques at various pulse patterns to collect functions from nanoseconds milliseconds. obtained sample all different are very good agreement with expected Brownian motions silica...
We have investigated the laser induced ultrafast dynamics of Gd 4f spins at surface CoxGd100-x alloys by means surface-sensitive and time-resolved dichroic resonant Auger spectroscopy. observed that quenching magnetic order occur on a much longer time scale than previously reported in bulk sensitive experiments. In parallel, we characterized static structural properties these combining Physical Property Measurement System (PPMS) magnetometry with X-ray Magnetic Circular Dichroism absorption...
Femtosecond laser pulses can be used to induce ultrafast changes of the magnetization in magnetic materials. Several microscopic mechanisms have been proposed explain observations, including transport ultrashort spin-polarized hot-electrons (SPHE). Such spin currents find growing interest because recent challenges spintronics however they are only poorly characterized. One key is characterize and behind SPHE induced manipulation magnetization, especially case technologically relevant...
We explore the impact of optical excitation using two interfering ultrashort pulses on ultrafast magnetization dynamics. Our investigation focuses Pt/Co/Pt multilayers and TbCo alloy samples, employing a dual pump approach. observe significant variations in dynamics suppression subsequent recovery when triggered with same polarization-essentially meeting conditions for interference. Conversely, cross-polarized beams exhibit expected similarity to that single pulse. Delving into underlying...
Abstract We report on the feasibility of Fourier transform holography in hard X-ray regime using a Free Electron Laser source. Our study shows successful single and multi-pulse holographic reconstructions nanostructures. observe beam-induced heating sample exposed to intense pulses leading reduced visibility reconstructions. Furthermore, we extended our exploring recording with split-and-delay optics. paves way towards studying dynamics at sub-nanosecond timescales atomic lengthscales.
In this study, we have investigated the effect of Mn addition on texture, phase formation, and magnetic properties L10 FePt thin films. FePt/Mn/FePt trilayers were processed by rapid thermal annealing in temperature range 650 – 800°C for 30 s N2 atmosphere. It is shown that up to 10 at.% supports L10(001)-texture formation resulting large perpendicular anisotropy. However, it observed only partially incorporated into lattice. was found diffuses through top layer sample surface, promoting...
We have studied the nature of optically induced short-range magnetic fluctuations occurring at 10-nm length scale during ultrafast demagnetization in ferromagnetic Co/Pt multilayers. The time resolved probing magnetization dynamics was performed with femtosecond soft x-ray pulses European free-electron laser. A transient high-q scattering accompanying and directly correlated to destruction maze domain network has been observed picosecond wave vector region 0.2–0.8nm−1. This a purely is...
Abstract Ultrashort and intense extreme ultraviolet (XUV) X-ray pulses readily available at free-electron lasers (FELs) enable studying non-linear light−matter interactions on femtosecond timescales. Here, we report the fluence dependence of magnetic scattering Co/Pt multilayers, using FERMI FEL’s 70-fs-long single double XUV pulses, latter with a temporal separation 200 fs, photon energy slightly detuned to Co M2,3 absorption edge. We observe quenching in that sets-in already...
Direct 2D spatial-coherence measurements are increasingly gaining importance at synchrotron beamlines, especially due to present and future upgrades of facilities diffraction-limited storage rings. We a method determine the spatial coherence radiation in direct particularly simple way by using Fourier-analysis conjunction with curved gratings. photon-beam monitoring provided grating circumvents otherwise necessary separate determination illuminating intensity distribution required for...
Three-dimensional photon correlation spectroscopy (3D PCS) is a well-known technique developed to suppress multiple scattering contributions in functions, which are inevitably involved when an optical laser employed investigate dynamics turbid system. Here, we demonstrate proof-of-principle study of 3D PCS the hard X-ray regime. We employ cross-correlator measure silica colloidal nanoparticles dispersed polypropylene glycol. The obtained cross functions show very good agreement with...
One of the intriguing problems modern magnetism is unravelling non-equilibrium spin dynamics following laser excitation on nanometer length scale. In this work ultrafast magnetic behavior thin Co/Pt multilayers studied by resonant SAXS in transmission geometry. We have for first time observed a very bright transient scattering from scale fluctuations.
Abstract Free-electron lasers (FELs) provide unique possibilities in investigating matter down to femtosecond time and nanometer length scales, as well the regime of non-linear light-matter interaction. Due nature FEL sources, produced beam is significantly more unstable than beams by 3 rd generation synchrotrons. As a result, pulse-resolved normalization measurement data becomes essential can be challenging. The intensity monitors permanently installed at facility might indeed accurately...
Abstract We report on a Fourier transform holography study, employing hard X-ray energies at 3rd generation storage ring. Nano-structures of various sizes and shapes have been measured in ultra small angle x-ray scattering configuration reaching resolution the holographic reconstructions about 50 nm. Reliable holograms obtained with 6.9×10 6 incident photons. Our results provide an important step forward towards routine split-pulse measurements FEL sources 4th ultralow-emittance sources.
Terahertz (THz) light pulses can be used for an ultrafast coherent manipulation of the magnetization. Driving magnetization at THz frequencies is currently fastest way writing magnetic information in ferromagnets. Using time-resolved resonant scattering, we gain new insights to THz-driven dynamics on nanometer length scales. We observe demagnetization and oscillations that are governed by a time-dependent damping. This damping determined interplay lattice heating anisotropy reduction...
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, we present the results first megahertz rate scattering experiments Spectroscopy Coherent Scattering (SCS) instrument European...