A5074746987- Magnetic properties of thin films
- Semiconductor materials and devices
- Advanced Chemical Physics Studies
- Electron and X-Ray Spectroscopy Techniques
- Graphene research and applications
- Surface and Thin Film Phenomena
- Electronic and Structural Properties of Oxides
- X-ray Spectroscopy and Fluorescence Analysis
- 2D Materials and Applications
- Molecular Junctions and Nanostructures
- Advanced X-ray Imaging Techniques
- Semiconductor materials and interfaces
- Atomic and Molecular Physics
- Quantum Dots Synthesis And Properties
- Chalcogenide Semiconductor Thin Films
- Nanowire Synthesis and Applications
- Ferroelectric and Piezoelectric Materials
- Quantum and electron transport phenomena
- Advanced Electron Microscopy Techniques and Applications
- Magnetic Properties and Applications
- Boron and Carbon Nanomaterials Research
- Perovskite Materials and Applications
- Particle Accelerators and Free-Electron Lasers
- Magnetic Properties of Alloys
- Physics of Superconductivity and Magnetism
Centre National de la Recherche Scientifique
2010-2024
Laboratoire de Physique Théorique de la Matière Condensée
2017-2024
École Polytechnique
2017-2024
Synchrotron soleil
2014-2023
Laboratoire de physique de la matière condensée
2017-2022
Université Paris-Saclay
2012-2021
Universität Hamburg
2018
University of California, San Diego
2018
Istituto Officina dei Materiali
2018
European Theoretical Spectroscopy Facility
2018
Two-dimensional layered MoS2 shows great potential for nanoelectronic and optoelectronic devices due to its high photosensitivity, which is the result of indirect direct band gap transition when bulk dimension reduced a single monolayer. Here, we present an exhaustive study alignment relativistic properties van der Waals heterostructure formed between layers graphene. A sharp, high-quality MoS2-graphene interface was obtained characterized by micro-Raman spectroscopy, high-resolution X-ray...
Stacking two-dimensional materials in so-called van der Waals (vdW) heterostructures, like the combination of GaSe and graphene, provides ability to obtain hybrid systems that are suitable design optoelectronic devices. Here, we report structural electronic properties direct growth multilayered by molecular beam epitaxy on graphene. Reflection high-energy electron diffraction images exhibited sharp streaky features indicative a high-quality layer produced via vdW epitaxy. Micro-Raman...
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 results on the self-assembly of silicon nanoribbons (NRs) (2 × 1) reconstructed Au(110) surface under ultra-high vacuum conditions. Upon adsorption 0.2 monolayer (ML) silicon, reconstruction is replaced by an ordered alloy. Above this coverage, a new superstructure revealed low energy electron diffraction (LEED), which becomes sharper at 0.3 Si ML. This corresponds to all oriented along [1¯10] direction as LEED and scanning tunneling microscopy (STM). STM high-resolution...
The experimental valence band photoemission spectrum of semiconductors exhibits multiple satellites that cannot be described by the GW approximation for self-energy in framework many-body perturbation theory. Taking silicon as a prototypical example, we compare high energy spectra with calculations and analyze origin failure. We then propose an to functional differential equation determines exact one-body Green's function, whose solution has exponential form. This yields calculated spectrum,...
Abstract We describe an experimental method to probe the adsorption of water at surface isolated, substrate-free TiO 2 nanoparticles (NPs) based on soft X-ray spectroscopy in gas phase using synchrotron radiation. To understand interfacial properties between and surface, a shell was adsorbed NPs. used two different ways control hydration level NPs: first scheme, initially solvated NPs were dried second one, dry generated thanks commercial aerosol generator exposed vapor. XPS identify...
Two-dimensional (2D) materials have recently been the focus of extensive research. By following a similar trend as graphene, other 2D including transition metal dichalcogenides (MX2) and mono-chalcogenides (MX) show great potential for ultrathin nanoelectronic optoelectronic devices. Despite weak nature interlayer forces in semiconducting MX materials, their electronic properties are highly dependent on number layers. Using scanning tunneling microscopy spectroscopy (STM/STS), we demonstrate...
The stacking order of multilayer graphene has a profound influence on its electronic properties. In particular, it been predicted that rhombohedral sequence displays very flat conducting surface state: the longer sequence, flatter band. such band, role electron-electron correlation is enhanced, possibly resulting in high Tc superconductivity, magnetic order, or charge density wave order. Here we demonstrate multilayers are easily obtained by epitaxial growth 3C-SiC(111) 2° off-axis...
Nitrogen doping of graphene is great interest for both fundamental research to explore the effect dopants on a 2D electrical conductor and applications such as lithium storage, composites, nanoelectronic devices. Here, we report modifications electronic properties epitaxial thanks introduction, during growth, nitrogen-atom substitution in carbon honeycomb lattice. High-resolution transmission microscopy low-energy electron investigations indicate that nitrogen-doped uniform at large scale....
Structural defects in the molybdenum disulfide (MoS2) monolayer are widely known for strongly altering its properties. Therefore, a deep understanding of these structural and how they affect MoS2 electronic properties is fundamental importance. Here, we report on incorporation atomic hydrogen monolayered to tune defects. We demonstrate that single layer can be tuned from intrinsic electron (n) hole (p) doping via controlled exposure at room temperature. Moreover, this hydrogenation process...
State-of-the-art theoretical methods fail in describing the optical absorption spectrum, band gap, and onset of ${\mathrm{Cu}}_{2}\mathrm{O}$. We have extended a recently proposed self-consistent quasiparticle approach, based on $GW$ approximation, to calculation spectra, including excitonic effects. The structure compares favorably with our present angle-resolved photoemission measurements. effects these realistic screening provide reliable which allows for revised interpretation its main...
High-energy resolution photoelectron spectroscopy (ΔE < 200 meV) is used to investigate the internal structure of semiconductor quantum dots containing low Z-contrast elements. In InP/ZnS core/shell nanocrystals synthesized using a single-step procedure (core and shell precursors added at same time), homogeneously alloyed InPZnS core evidenced by quantitative analysis their In3d5/2 spectra recorded variable excitation energy. When two-step method InP nanocrystal synthesis followed subsequent...
A new insertion device beamline is now operational on straight section 8 at the SOLEIL synchrotron radiation source in France. The and experimental station were developed to optimize study of dynamics electronic magnetic properties materials. Here we present main technical characteristics installation general principles behind them. composed two APPLE II type devices. monochromator with plane gratings spherical mirrors working energy range 40–1500 eV. It equipped VLS, VGD allow user...
A cheap and more environmentally friendly method for the synthesis of high quality PbS nanoparticles in olive oil at 60 °C has been developed. Carefully controlling conditions reactions leads to with well-defined sizes, band gaps between 1.72 0.88 eV. The were characterized by XRD, HRTEM, NIR absorption spectroscopy, X-ray photoelectron spectroscopy (XPS) a fluorescence lifetime experiment based on time-correlated single photon counting (TCSPC) technique. Photoelectrochemical study carried...
The growth of large and uniform graphene layers remains very challenging to this day due the close correlation between electronic transport properties layer morphology. Here, we report synthesis large-scale mono- bilayers on off-axis 6H-SiC(0001) substrates. originality our approach consists fine control mode by precise Si sublimation rate. Moreover, take advantage presence nanofacets substrate grow a with good long-range order. We believe that represents significant step toward scalable...
A promising route towards nanodevice applications relies on the association of graphene and transition metal dichalcogenides with hexagonal boron nitride ($h\text{\ensuremath{-}}\mathrm{BN}$). Due to its insulating nature, $h\text{\ensuremath{-}}\mathrm{BN}$ has emerged as a natural substrate gate dielectric for graphene-based electronic devices. However, some fundamental properties bulk remain obscure. For example, band structure position Fermi level have not been experimentally resolved....
Ultrafast transient absorption measurements have been used to study multiple exciton generation in solutions of PbS nanoparticles vigorously stirred avoid the effects photocharging. The threshold and slope efficiency are found be 2.5 ± 0.2 ×E(g) 0.34 0.08, respectively. Photoemission as a function nanoparticle size ageing show that position valence band maximum is pinned by surface effects, thick layer oxide rapidly formed at surfaces on exposure air.
Abstract Stacking various two-dimensional atomic crystals is a feasible approach to creating unique multilayered van der Waals heterostructures with tailored properties. Herein for the first time, we present controlled preparation of large-area h-BN/graphene via simple chemical deposition h-BN layers on epitaxial graphene/SiC(0001). Van forces, which are responsible cohesion multilayer system, give rise an abrupt interface without interdiffusion between graphene and h-BN, as shown by X-ray...
Hybrid heterostructures based on bulk GaN and two-dimensional (2D) materials offer novel paths toward nanoelectronic devices with engineered features. Here, we study the electronic properties of a mixed-dimensional heterostructure composed intrinsic $n$-doped $\mathrm{Mo}{\mathrm{S}}_{2}$ flakes transferred $p$-doped GaN(0001) layers. Based angle-resolved photoemission spectroscopy (ARPES) high resolution x-ray (HR-XPS), investigate structure modification induced by interlayer interactions...
Two-dimensional monochalcogenides (MX) have been identified as a unique and promising class of layered materials in recent years. The valence band single-layer MX, predicted by theory, is inverted into bow-shaped (often referred to an sombrero) relatively flat dispersion, which expected give rise strongly correlated effects. inversion leads indirect gap, consistent with photoluminescence (PL) experiments, but PL provides no direct evidence the band. Here we demonstrate for hexagonal MX...
Monolayers of transition metal dichalcogenides are ideal materials to control both spin and valley degrees freedom either electrically or optically. Nevertheless, optical excitation mostly generates excitons species with inherently short lifetime spin/valley relaxation time. Here we demonstrate a very efficient pumping resident electrons in n-doped WSe2 WS2 monolayers. We observe that, using continuous wave laser appropriate doping densities, negative trion doublet lines exhibit circular...
Synchrotron radiation time structure is becoming a common tool for studying dynamic properties of materials. The main limitation often the wide domain user would like to access with pump-probe experiments. In order perform photoelectron spectroscopy experiments over scales from milliseconds picoseconds it mandatory measure at which each measured was created. For this reason usual CCD camera-based two-dimensional detection electron energy analyzers has been replaced by new delay-line detector...
Surface metallization of ${\mathrm{SrTiO}}_{3}(001)$ by hydrogen adsorption is experimentally confirmed for the first time photoemission spectroscopy and surface conductivity measurements. The metallic state assigned to a quantized in space-charge layer induced electron doping from atoms. measured two-dimensional (2D) well above 2D Ioffe-Regel limit indicating that system conduction regime. mean free path estimated be several nanometers at room temperature.