A5052640258- Advanced X-ray Imaging Techniques
- Advanced Electron Microscopy Techniques and Applications
- Magnetic properties of thin films
- Crystallography and Radiation Phenomena
- Particle Accelerators and Free-Electron Lasers
- X-ray Spectroscopy and Fluorescence Analysis
- Astrophysical Phenomena and Observations
- Magnetic Properties of Alloys
- Physics of Superconductivity and Magnetism
- Magnetic Properties and Applications
- Digital Holography and Microscopy
- Superconducting Materials and Applications
- Theoretical and Computational Physics
- High-pressure geophysics and materials
- Advanced Chemical Physics Studies
- Laser-Plasma Interactions and Diagnostics
- Force Microscopy Techniques and Applications
- Advanced X-ray and CT Imaging
- Molecular Junctions and Nanostructures
- Advanced Memory and Neural Computing
- Quantum and electron transport phenomena
- Magneto-Optical Properties and Applications
- Magnetic and transport properties of perovskites and related materials
- Electron and X-Ray Spectroscopy Techniques
Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy
2016-2020
Canadian Light Source (Canada)
2017-2018
Elettra-Sincrotrone Trieste S.C.p.A.
2017
Laboratoire de Chimie Physique - Matière et Rayonnement
2017
Centre National de la Recherche Scientifique
2017
Technische Universität Berlin
2013-2016
Helmholtz-Zentrum Berlin für Materialien und Energie
2012-2015
During ultrafast demagnetization of a magnetically ordered solid, angular momentum has to be transferred between the spins, electrons, and phonons in system on femto- picosecond timescales. Although intrinsic spin-transfer mechanisms are intensely debated, additional extrinsic arising due nanoscale heterogeneity have only recently entered discussion. Here we use femtosecond X-ray pulses from free-electron laser study thin film samples with magnetic domain patterns. We observe an...
Fourier transform holography is a highly efficient and robust imaging method, suitable for single-shot at coherent X-ray sources. In its common implementation, the image contrast limited by reference signal generated small pinhole aperture. Increased diameters improve signal, whereas resolution diminished. Here we report new concept to decouple spatial from employing Fresnel zone plate provide beam. Superimposed on-axis images of distinct foci are separated with novel algorithm. Our method...
We present results of single-shot resonant magnetic scattering experiments Co/Pt multilayer systems using 100 fs long ultraintense pulses from an extreme ultraviolet (XUV) free-electron laser. An x-ray-induced breakdown the channel during pulse duration is observed at fluences 5 J/cm(2). Simultaneously, speckle contrast high-fluence pattern significantly reduced. performed simulations nonequilibrium evolution system XUV duration. find that electronic state sample strongly perturbed first few...
We present an element specific and spatially resolved view of magnetic domains in Co/Pt heterostructures the extreme ultraviolet spectral range. Resonant small-angle scattering coherent imaging with Fourier-transform holography reveal nanoscale domain networks via dichroism Co at M2,3 edges as well strong dichroic signals O2,3 N6,7 Pt. demonstrate for first time simultaneous, two-color a free-electron laser facility paving way direct real space access to ultrafast magnetization dynamics...
Exploiting x-ray magnetic circular dichroism at the L-edges of 3d transition metals, Fourier transform holography has become a standard technique to investigate samples with sub-100 nm spatial resolution. Here, imaging in 21 wavelength regime using M-edge is demonstrated. Ultrafast pulses this are increasingly available from both laser- and accelerator-driven soft sources. We explain adaptations concerning sample preparation data evaluation compared conventional 1 range. find correction...
The evolution of a magnetic domain structure upon excitation by an intense, femtosecond infrared (IR) laser pulse has been investigated using single-shot based time-resolved resonant x-ray scattering at the free electron LCLS. A well-ordered stripe pattern as present in thin CoPd alloy film used prototype for this study. fluence IR pump was sufficient to lead almost complete quenching magnetization within ultrafast demagnetization process taking place first few hundreds femtoseconds...
We systematically study the fluence dependence of resonant scattering cross-section from magnetic domains in Co/Pd-based multilayers. Samples are probed with single extreme ultraviolet (XUV) pulses femtosecond duration tuned to Co M_{3,2} absorption resonances using FERMI@Elettra free-electron laser. report quantitative data over 3 orders magnitude fluence, covering 16 mJ/cm^{2}/pulse 10 000 pulse lengths 70 fs and 120 fs. A progressive quenching diffraction is observed. Compression same...
We present magnetic domain states in a material configuration with high (perpendicular) anisotropy and particularly low pinning. This material, B-doped Co/Pt multilayer configuration, exhibits strong contrast x-ray transmission experiments, making it apt for dynamic imaging modern synchrotron techniques, providing spatial temporal resolution simultaneously. By analyzing the static spin structures nanodisks at variable external fields, we show that CoB/Pt multilayers exhibit enough wall...
We demonstrate an x-ray imaging method that combines Fourier transform holography with tomography ('tomoholography') for three-dimensional (3D) microscopic imaging. A 3D image of a diatom shell spatial resolution 140 nm is presented. The experiment realized by using small gold sphere as the reference wave source holographic This setup allows us to rotate sample and collect number 2D projections tomography.
A cryo scanning transmission X-ray microscope, the cryo-STXM, has been designed and commissioned at Canadian Light Source synchrotron. The instrument is to operate from 100 4000 eV (λ = 12.4 − 0.31 nm). Users can insert a previously frozen sample, through load lock, rotate it ±70° in beam collect tomographic data sets. sample be maintained for extended periods 92 K primarily suppress radiation damage pressure on order of 10−9 Torr contamination. achieved spatial resolution (30 nm) spectral...
In preparation for real space studies of magnetic domains in a pump-probe setup at free-electron laser sources, it is necessary to develop an imaging method compatible with the linearly polarized radiation available these sources. We present results from prototype experiment performed synchrotron source BESSY II, using modification existing phase retrieval techniques. Our show that possible image linear light, and we introduce concept reliability map our reconstructions Gabor transforms.
We demonstrate how information about the three-dimensional structure of an object can be extracted from a single Fourier-transform Xray hologram.In contrast to lens-based 3D imaging approaches that provide depth specimen utilizing several images different angles or via adjusting focus depths, our method capitalizes on use holographically encoded phase and amplitude object's wavefield.It enables single-shot measurements objects at coherent X-ray sources.As ratio longitudinal resolution over...
Ptychography is a lensless imaging technique that aims to reconstruct an object from set of coherent diffraction patterns originating different and partially overlapping sample illumination areas. For successful convergence the iterative algorithms used, scan positions have be known with very high accuracy. Here, we present method allows directly encode this information in without need accurate position encoders. Our approach relies on combining ptychography another method, namely...
The spatial resolution of microscopic images acquired via X-ray Fourier-transform holography is limited by the source size reference wave and numerical aperture detector. We analyze interplay between both influences show how they are matched in practice. further identify, high frequencies translate to imaging artifacts holographic reconstructions where mainly beam limits resolution. As a solution, three methods introduced based on post-processing reconstruction. comprise apodization...
The free-electron laser (FEL) sources FLASH in Hamburg, LCLS at Stanford, and FERMI Trieste provide XUV to soft X-ray radiation (FLASH FERMI) or hard (LCLS) with unprecedented parameters terms of ultrashort pulse length, high photon flux, coherence. These properties make FELs ideal tools for studying ultrafast dynamics matter on a previously unaccessible level. This paper first reviews results obtained FEL during the last few years field magnetism research. We start pioneering experiments...
We present dichroic x-ray lensless magnetic imaging by Fourier transform holography with an extended reference scheme via a modified uniformly redundant array (mURA). Holographic images of domains simultaneously generated single pinhole as well mURA are compared respect to the signal-to-noise ratio (SNR) function exposure time. apply this approach for spectro-holographic ferromagnetic domain patterns in Co/Pt multilayer films. Soft x-rays wavelengths 1.59 nm (Co L3 absorption edge) and 20.8...
An endstation for pump–probe small-angle X-ray scattering (SAXS) experiments at the free-electron laser in Hamburg (FLASH) is presented. The houses a solid-state absorber, optical incoupling experiments, time zero measurement, sample chamber, and detection unit. It can be used all FLASH beamlines whole photon energy range offered by FLASH. capabilities of setup are demonstrated showing results resonant magnetic SAXS measurements on cobalt-platinum multilayer samples grown freestanding $\rm...
Skyrmions are topologically protected particle-like configurations, with a topological complexity described by their Skyrmion number. In magnetic systems, they have been numerically predicted to exhibit rich dynamics, such as the gyrotropic and breathing modes, dominated topology. Recent experimental advances brought static manipulation well under control. However, dynamical behaviour is largely unexplored experimentally. this work, we provide first direct observation of eigenmode skyrmion...
Many fundamental processes in magnetism take place on a nanometer length and sub-picosecond time scale. An important example of such phenomena is ultrafast, spin-polarized transport laser-excited hot electrons, which now being recognized as playing crucial role for novel spintronic devices optically induced magnetic switching. Recent experimental examples include the demonstration all-optical helicity dependent control currents at interfaces [1 T.J. Huisman, Nature Nanotechn.,...