A5048350811- X-ray Spectroscopy and Fluorescence Analysis
- Electron and X-Ray Spectroscopy Techniques
- Magnetic properties of thin films
- Advanced Electron Microscopy Techniques and Applications
- Crystallography and Radiation Phenomena
- Atomic and Molecular Physics
- Force Microscopy Techniques and Applications
- Nanowire Synthesis and Applications
- Photonic and Optical Devices
- Semiconductor Quantum Structures and Devices
- ZnO doping and properties
- Magnetic and transport properties of perovskites and related materials
- Transition Metal Oxide Nanomaterials
- X-ray Diffraction in Crystallography
- Optical measurement and interference techniques
- Advanced Chemical Physics Studies
- Rare-earth and actinide compounds
- Advanced X-ray Imaging Techniques
- Photorefractive and Nonlinear Optics
- Advanced Condensed Matter Physics
- Surface and Thin Film Phenomena
- Semiconductor materials and interfaces
- Iron oxide chemistry and applications
- Magnetism in coordination complexes
- Perovskite Materials and Applications
Politecnico di Milano
2014-2023
Center for Nano Science and Technology
2016-2023
Italian Institute of Technology
2016-2023
Free University of Bozen-Bolzano
2023
Polytechnic University of Turin
2019
University of Milano-Bicocca
2009-2018
National Interuniversity Consortium for the Physical Sciences of Matter
2007-2015
Ente Regionale per i Servizi all'Agricoltura e alle Foreste
2009
European Commission
2009
Universidade do Estado do Rio de Janeiro
2001-2005
Polarized oxygen Kα x-ray absorption and emission spectra, near 530 eV, of a single crystal Cs2UO2Cl4 are reported. With the aid density functional theory calculations data, relative energies empty molecular orbitals having primarily uranium 5f 6d character assigned. The spectra give access to energy excitations these from various filled valence-shell orbitals. These support conclusion optical that valence σu occupied occur at substantially lower than those σg, πg, πu This latter group have...
We have measured the resonant inelastic x-ray scattering (RIXS) spectra at Cu L3 edge in a variety of cuprates. Exploiting considerably improved energy resolution (0.8 eV) we recorded significant dependencies on sample composition and orientation, geometry, incident photon polarization. The RIXS final states correspond to two families electronic excitations, having local (dd excitations) nonlocal (charge-transfer) character. dd splitting can be estimated with simple crystal field model....
Orbital ordering (OO) in the layered perovskite La0.5Sr1.5MnO4 has been investigated using enhanced sensitivity of soft x-ray resonant diffraction at Mn L edges. The energy dependence an OO peak over L(2,3) edges is compared to ligand-field calculations allowing a distinction between influences Jahn-Teller distortions and spin correlations. L1 edge remarkably different from that observed K edge.
Resonant inelastic x-ray scattering (RIXS) at the L2,3 edges of 3d transition metal compounds has recently become a high resolution spectroscopic technique thanks to improvements in instrumentation. We have chosen prototypical case NiO explore various levels interpretation applicable L3 RIXS spectra strongly correlated electron systems. Starting from set experimental data measured across Ni absorption edge with 550 meV combined energy resolution, we analyse rich spectral structure within an...
The resonant inelastic x-ray scattering (RIXS) of $\mathrm{MnO}$ measured with high energy resolution across the ${\mathrm{L}}_{2,3}$ absorption edges Mn is characterized by a very rich spectral structure due to local electronic excitations. spectra are dominated dd and charge transfer excitations, both dipole allowed in RIXS process. strongly depend on polarization incident photons. This vast experimental basis allows an accurate determination main parameters theoretical models used...
We have investigated the magnetic structure of a Sr2FeMoO6 single crystal by X-ray circular dichroism at L2,3 edges Fe and Mo sites. The spin moments we find on (3.05μB) ( − 0.32μB) give, for first time, direct confirmation their ferrimagnetic ordering. presence finite moment together with only very small orbital both confirms that predicted half-metallicity compound is due to configuration five localized d electrons forming high-spin one s antiparallel delocalized electron shared between other
An in-plane perpendicular magnetic coupling between Ni80Fe20 and Co has been found in NiFe/NiO/Co trilayers for a NiO thickness ranging from 4 to 25 nm by magneto-optical Kerr effect x-ray circular dichroism measurements. In the easy magnetization direction of layer, coercive field H(C) increases when layer t(NiO) increases. Because coupling, is always larger than NiO/Co bilayers with same thicknesses. The saturation NiFe H(S) decreases increases, indicating weakening coupling. Numerical...
X-ray magnetic-circular-dichroism (XMCD) spectra on the molecular superparamagnets $[{\mathrm{Mn}}_{12}{\mathrm{O}}_{12}{(\mathrm{C}\mathrm{H}}_{3}{\mathrm{C}\mathrm{O}\mathrm{O})}_{16}{(\mathrm{H}}_{2}{\mathrm{O})}_{24}]\ensuremath{\cdot}{2\mathrm{C}\mathrm{H}}_{3}{\mathrm{COOH}\mathrm{\ensuremath{\cdot}}4\mathrm{H}}_{2}\mathrm{O}$ (in short Mn12) and...
Accurate wavelength measurements in the molecular nitrogen pulsed laser have been made. Four new ir bands were discovered. In addition, about two hundred stimulated emission lines belonging to first and second positive systems obtained identified as rotational quantum number. An analysis of possible pumping mechanisms accordance with experimental results is given.
We performed bulk-sensitive x-ray absorption (XAS) in the partial fluorescence yield (PFY) mode, and resonant emission (RXES) measurements of solid solution Sc (7 at.%):$\mathrm{Ce}$ at $\mathrm{Ce}\phantom{\rule{0.3em}{0ex}}{\mathrm{L}}_{3}\phantom{\rule{0.3em}{0ex}}(2p\ensuremath{\rightarrow}5d)$ ${\mathrm{M}}_{4,5}\phantom{\rule{0.3em}{0ex}}(3d\ensuremath{\rightarrow}4f)$ edges. deduce an increasing $4f$-band hybridization from $\ensuremath{\gamma}$-phase stable room temperature to...
Tungsten oxide nanowires have been synthesized by vacuum annealing in the range 500–710 °C from amorphous-like tungsten films, deposited on a Si(100) substrate pulsed laser deposition (PLD) presence of He background pressure. The oxygen required for formation is already adsorbed W matrix before annealing, its amount depending parameters. Nanowire crystalline phase and stoichiometry depend temperature, ranging W18O49-Magneli to monoclinic WO3. Sufficiently long induces micrometer-long...
A bilayer WO3 photoelectrode was obtained by radio frequency (RF) plasma sputtering in a reactive 40%O2/Ar atmosphere depositing two successive coatings on tungsten foil at different total gas pressures (3 Pa and 1.7 Pa, respectively), followed calcination 600 °C. Two monolayer samples deposited each of the sample inverted were also prepared. Their photoelectrocatalytic (PEC) activity evaluated both Incident Photon-to-Current Efficiency (IPCE) measurements separate evolution H2 O2 water...
Single-crystalline (001) Fe thin films were prepared by molecular beam epitaxy and covered epitaxial MgO barriers. The growth was confirmed to be layer as shown reflection high-energy electron diffraction, which allowed us prepare only two atomic planes of for spin polarization measurements. On the one hand, regular x-ray photoemission spectroscopy measurements evidenced a weak hybridization between O. Moreover, large magnetic moment at interface with circular dichroism These observations...
Dynamic magnetization reversal measurements have revealed a strong dependence of the exchange-coupling strength on maximum applied field for NiO/Co bilayers. Time-resolved Kerr measurements, performed at room temperature, show that coercive increases linearly with between two reversals. If is different in positive and negative directions, an exchange bias observed as well asymmetry behavior sides hysteresis loop. X-ray magnetic circular dichroism Ni ${L}_{2,3}$ edges indicate these effects...
Resonant inelastic x-ray scattering (RIXS) measurements performed jointly across the ${M}_{2,3}$ and ${L}_{3}$ absorption thresholds are used to study CoO local electronic structure supported by model calculations. The high-resolution experimental data provide a precise set of parameters describe correlated response valence electrons. same core-hole independent within single impurity Anderson is both $M$ $(3p\text{\ensuremath{-}}3d)$ $L$ $(2p\text{\ensuremath{-}}3d)$ resonances. This work...
The continued downscaling in SiGe heterostructures is approaching the point at which lateral confinement leads to a uniaxial strain state, giving high enhancements of charge carrier mobility. Investigation relaxation as induced by patterning continuous layer thus scientific and technological importance. In present work, single lithographically defined low-dimensional structures has been directly mapped via nanobeam x-ray diffraction. We found that nanopatterning able induce an anisotropic...
We fabricate site-controlled, ordered arrays of embedded Ga nanoparticles on Si, using a combination substrate patterning and molecular-beam epitaxial growth. The fabrication process consists two steps. droplets are initially nucleated in an array inverted pyramidal pits, then partially crystallized by exposure to As flux, which promotes the formation GaAs shell that seals nanoparticle within semiconductor layers. has been investigated through extensive chemical structural characterization...
Abstract A seeded FEL driven by a linac based on super conducting cavities, generating 10 8 –10 coherent photons per shot at 2–5 keV with 0.2–1 MHz of repetition rate, can address the need source devoted to fine analysis matter using linear spectroscopy technique. The seeding scheme described hereafter is multi-stage cascade upshifting radiation frequency factor 20–40. x-ray range be achieved seed constituted flash in extreme ultraviolet provided an oscillator operating 12–14 nm. whole chain...
We measured circular dichroism in resonant x-ray scattering ${3d}^{n}\ensuremath{\rightarrow}{2p}^{5}{3d}^{n+1}\ensuremath{\rightarrow}{3s}^{1}{3d}^{n+1}$ with incidence perpendicular to the magnetization where absorption vanishes. The advantages of photon over other techniques make it possible study a wide range materials. Ni ${L}_{3}$ $\mathrm{NiFe}{}_{2}\mathrm{O}{}_{4}$ is $(28\ifmmode\pm\else\textpm\fi{}5)%$ agreement localized model. In metal Co reduced...
In this work, we describe the consequences of oxygen and metal-ion deficiency for magnetic properties a oxide in bulk thin-film form. The influence off stoichiometry on valence iron atoms local structural configuration these is investigated correlation with Curie temperatures associated microscopic parameters, such as exchange integrals. Combining both information obtained by x-ray absorption spectroscopy at $\text{Fe}\text{ }K$ edge integrals determined from temperature-resolved...
PoLIFEMo (Polarized Light Improved Flux Efficiency Monochromator) is the name of a spherical grating monochromator designed with purpose maximizing photon intensity on sample. The device mainly conceived to improve performances an x-ray emission spectrometer, whose limiting factor often counting rate. By keeping exit slit fixed, it possible get small spot size (∼35 μm vertically) sample placed just near slit, without need postgrating refocusing optics. No entrance used because low beam...