A5065167504- Magnetic properties of thin films
- X-ray Spectroscopy and Fluorescence Analysis
- Electron and X-Ray Spectroscopy Techniques
- Advanced X-ray Imaging Techniques
- Advanced Chemical Physics Studies
- Crystallography and Radiation Phenomena
- Atomic and Molecular Physics
- Magnetic Properties and Applications
- Surface and Thin Film Phenomena
- Magnetic and transport properties of perovskites and related materials
- Electronic and Structural Properties of Oxides
- Theoretical and Computational Physics
- Advanced Electron Microscopy Techniques and Applications
- Semiconductor materials and interfaces
- Physics of Superconductivity and Magnetism
- ZnO doping and properties
- Transition Metal Oxide Nanomaterials
- Advanced Condensed Matter Physics
- Magnetic Properties of Alloys
- X-ray Diffraction in Crystallography
- Nuclear physics research studies
- Semiconductor materials and devices
- Multiferroics and related materials
- Ga2O3 and related materials
- Particle Accelerators and Free-Electron Lasers
Sorbonne Université
2013-2024
Centre National de la Recherche Scientifique
2013-2024
Synchrotron soleil
2015-2024
Institut des NanoSciences de Paris
2013-2024
Elettra-Sincrotrone Trieste S.C.p.A.
2024
Ikerbasque
2023
CIC nanoGUNE
2023
Centro Internacional Franco-Argentino de Ciencias de la Información y de Sistemas
2020
STMicroelectronics (Italy)
2018
Université Paris Cité
1991-2017
Abstract Magneto-optical (MO) effects, viz. magnetically induced changes in light intensity or polarization upon reflection from transmission through a magnetic sample, were discovered over century and half ago. Initially they played crucially relevant role unveiling the fundamentals of electromagnetism quantum mechanics. A more broad-based relevance wide-spread use MO methods, however, remained quite limited until 1960s due to lack suitable, reliable easy-to-operate sources. The advent...
We show that linear polarized x-ray-absorption spectroscopy can be used to measure the temperature and thickness dependence of magnetic moments in NiO thin films. demonstrate both long-range order nearest-neighbor spin-spin correlations revealed. (100) films with thicknesses 5, 10, 20 monolayers epitaxially grown on MgO are studied. The N\'eel is found strongly reduced from bulk value even for monolayer film.
Abstract Two series of experiments on well‐characterized systems were performed to examine the probing depth soft x‐ray absorption spectroscopy (XAS) measured in total‐electron‐yield (TEY) mode. First we Ni 2 p 3/2 spectra Ni(100) covered with Tb as a function overlayer thickness. Secondly recorded O 1s Ta 5 films produced by controlled anodic oxidatio foils oxide The mean (MPD) was found be much shorter than previously assumed (for 1s, only 1.9 nm). relative importance those cascade...
We present high-resolution 2p x-ray-absorption spectra from 3d transition metals M in three series of pseudobinary and pseudoternary oxides. show how the detailed shape multiplet within can be used to determine valence ions. The early-transition-metal compounds dramatic changes as a function substitution due occupancy, indicating that extra holes or electrons are located predominantly at 3d-metal sites. This contrasts strongly with behavior late-transition-metal compounds, for which charges...
We present the first single-shot images of ferromagnetic, nanoscale spin order taken with femtosecond x-ray pulses. X-ray-induced electron and dynamics can be outrun pulses shorter than 80 fs in investigated fluence regime, no permanent aftereffects samples are observed below a 25 mJ/cm2. Employing resonant spatially muliplexed holography results low imaging threshold 5 Our open new ways to combine ultrafast laser spectroscopy sequential snapshot on single sample, generating movie excited...
We report on the experimental evidence of magnetic helicoidal dichroism, observed in interaction an extreme ultraviolet vortex beam carrying orbital angular momentum with a vortex. Numerical simulations based classical electromagnetic theory show that this dichroism is interference light modes different momenta, which are populated after between and topology. This observation gives insight into interplay magnetism sets framework for development new analytical tools to investigate ultrafast...
Electromagnetic waves possessing orbital angular momentum (OAM) are powerful tools for applications in optical communications, quantum technologies, and tweezers. Recently, they have attracted growing interest since can be harnessed to detect peculiar helical dichroic effects chiral molecular media magnetic nanostructures. In this work, we perform single-shot per position ptychography on a nanostructured object at seeded free-electron laser, using extreme ultraviolet OAM beams of different...
The strongly correlated and nominally trivalent Ni oxides R${\mathrm{NiO}}_{3}$ (R=Pr, Nd) show a sharp metal to insulator transition at ${\mathit{T}}_{\mathit{M}\mathrm{\ensuremath{-}}\mathit{I}}$=135 200 K, respectively. Rare-earth (3d), (1s,2p), O (1s) x-ray absorption measurements have been performed above below the temperature in order investigate (a) valence of atoms (b) changes electronic structure across transition. Our results suggest that, contrast hole-doped...
Abstract The advent of free-electron laser (FEL) sources delivering two synchronized pulses different wavelengths (or colours) has made available a whole range novel pump–probe experiments. This communication describes major step forward using new configuration the FERMI FEL-seeded source to deliver with wavelengths, each tunable independently over broad spectral adjustable time delay. FEL scheme makes use seed beams and split radiator section generate extreme ultraviolet from distinct...
We show that the absorption spectra of magnetic iron oxides $({\mathrm{Fe}}_{3}{\mathrm{O}}_{4}, \ensuremath{\alpha}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3})$ exhibit strong angular-dependent saturation effects when measured in total electron yield mode. analyze quantitatively impact by independent evaluations probing depth (d), length (\ensuremath{\lambda}), and their ratio $(\ensuremath{\lambda}/d).$ Our estimates are $d\ensuremath{\approx}50\AA{},$...
SEXTANTS is a new SOLEIL beamline dedicated to soft X-ray scattering techniques. The beamline, covering the 50-1700 eV energy range, features two Apple-II undulators for polarization control and fixed-deviation monochromator. Two branch-lines host three end-stations elastic, inelastic coherent experiments.
The in-plane rotation of magnetic stripe domains in a 65-nm magnetostrictive ${\mathrm{Fe}}_{0.8}{\mathrm{Ga}}_{0.2}$ epitaxial film was investigated combining force microscopy, vibration sample magnetometry, and x-ray resonant scattering measurements. We analyzed the behavior pattern under application bias field along direction perpendicular to axis, made comparison with analogous at remanence. experimental results have been explained by means micromagnetic simulations, supported energy...
A soft x-ray spectrometer based on the use of an elliptical focusing mirror and a plane varied line spacing grating is described. It achieves both high resolution overall efficiency while remaining relatively compact. The instrument dedicated to resonant inelastic scattering studies. We set out how this optical arrangement was judged best able guarantee performance for 50 − 1000 eV range within achievable fabrication targets. AERHA (adjustable energy acceptance) operates with effective...
We have determined the effective attenuation length of photoelectrons over range kinetic energies from 4 to 6 keV in Co, Cu, Ge, and ${\mathrm{Gd}}_{2}{\mathrm{O}}_{3}$. The intensity substrate (Si) overlayer core level peaks was measured as a function thickness wedge-shaped overlayers. Experimental values vary between 45--50 \AA{} at 60--65 Ge. Smaller (30 50 \AA{}, respectively) are found Our results confirm that, for different classes materials, high energy photoemission spectroscopy has...
We have measured hard x-ray photoemission spectra of pure vanadium sesquioxide (${\mathrm{V}}_{2}{\mathrm{O}}_{3}$) across its metal-insulator transition. show that, in the metallic phase, a clear correlation exists between shakedown satellites observed $2p$ and $3p$ core-level coherent peak at Fermi level. Comparing experimental results dynamical mean-field theory calculations, we estimate Hubbard energy $U$ ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ ($4.20\ifmmode\pm\else\textpm\fi{}0.05\text{...
We report on the correlation between electrical behavior and valence band spectra of undoped Al-doped ZnO films, obtained by using x-ray photoelectron spectroscopy. Although Al-doping can induce a conductivity increase two orders magnitude, we show that gap persists there is no semiconductor–metal transition upon doping. For 3% film, measure reduction in ∼150meV with respect to 1% doped films. Our results suggest conduction mechanism proposed for at room temperature still dominates process
The instrument VOLPE (volume photoemission from solids) is an experimental setup dedicated to high energy (PE) experiments. equipped with electrostatic hemispherical spectrometer especially designed analyze electrons (up 10 keV) resolving power. In order attain resolution of a few tens millielectron volts, we and constructed input lens system, stability power supplies, low dark-count detector readout electronics. system has been tested now operational on the ID16 beamline at European...
The impressive progress in the performance of synchrotron radiation sources is nowadays driven by so-called `ultimate storage ring' projects which promise an unprecedented improvement brightness. Progress on detector side has not always been at same pace, especially as far soft X-ray 2D detectors are concerned. While most commonly used still based microchannel plates or CCD technology, recent developments CMOS (complementary metal oxide semiconductor)-type will play ever more important role...
We present high-resolution valence band and core level spectra of silver for photoelectron kinetic energies up to 8 keV. At these we estimate a surface contribution less than 3%. Taking advantage the favourable sp/d relative cross-sections, comparison with calculated density states is presented. observe an increasing photoemission intensity when approaching Fermi level, which assign free-electron-like character in 5p-band, whereas principal s-like located at bottom d-band. The difference...
We have measured magnetic circular x-ray dichroism (MCXD) in a remanently magnetized Ni(110) single crystal, with the light grazing incidence. Measuring absorption as function of applied field, we could draw hysteresis curve similar to one obtained magneto-optical Kerr effect on same crystal. Spectra taken linearly polarized show clear variations angle incidence sample is changed. The possible origins for this angular-dependent and its consequences MCXD measurements are discussed.
We use element-resolved IR-pump/extreme ultraviolet-probe experiments to disentangle the ultrafast interplay of magnetic sublattices an ordered crystalline alloy. As a paradigmatic example, we investigate case FeRh alloy, which shows delayed response for different components. Furthermore, detailed time-resolved magneto-optic study that data can be analyzed by only assuming Elliot-Yafet-like scattering, as underlying mechanism demagnetization, resulting in unexpected nonmonotonic dependence...