A5026910747- Electronic and Structural Properties of Oxides
- Magnetic and transport properties of perovskites and related materials
- Semiconductor materials and devices
- Advanced Condensed Matter Physics
- Atmospheric chemistry and aerosols
- Physics of Superconductivity and Magnetism
- Rare-earth and actinide compounds
- Air Quality and Health Impacts
- Iron-based superconductors research
- Atmospheric aerosols and clouds
- Inorganic Chemistry and Materials
- ZnO doping and properties
- Quantum Dots Synthesis And Properties
- Catalytic Processes in Materials Science
- Nuclear Physics and Applications
- Gas Sensing Nanomaterials and Sensors
- Nuclear Materials and Properties
- Atomic and Subatomic Physics Research
- Chalcogenide Semiconductor Thin Films
- Air Quality Monitoring and Forecasting
- Intermetallics and Advanced Alloy Properties
- Electron and X-Ray Spectroscopy Techniques
- solar cell performance optimization
- Atmospheric Ozone and Climate
- Thermal properties of materials
Synchrotron soleil
2014-2021
Université Paris-Saclay
2016-2021
Centre National de la Recherche Scientifique
2013-2021
Institut des Sciences Moléculaires d'Orsay
2020-2021
University of Luxembourg
2017-2019
Institut National de Physique Nucléaire et de Physique des Particules
2013-2018
Université Paris-Sud
2013-2018
Lawrence Berkeley National Laboratory
2012-2014
University of Würzburg
2012-2014
University of California, Berkeley
2013
2D electron systems (2DESs) in functional oxides are promising for applications, but their fabrication and use, essentially limited to SrTiO3 -based heterostructures, hampered by the need growing complex oxide overlayers thicker than 2 nm using evolved techniques. It is demonstrated that thermal deposition of a monolayer an elementary reducing agent suffices create 2DESs numerous oxides.
Bioavailable iron from atmospheric aerosol is an essential nutrient that can control oceanic productivity, thereby impacting the global carbon budget and climate. Particles collected on Okinawa Island during pollution transport event China were analyzed using complementary single particle techniques to determine source speciation. Comparing chemical composition spatial distribution of within ambient particles standard Asian mineral dust, it was determined field‐collected Fe‐containing have...
Abstract. Carbonaceous aerosols are responsible for large uncertainties in climate models, degraded visibility, and adverse health effects. The Aerosols Radiative Effects Study (CARES) was designed to study carbonaceous the natural environment of Central Valley, California, learn more about their atmospheric formation aging. This paper presents results from spectro-microscopic measurements particles collected during CARES at time a pollution accumulation event (27–29 June 2010), when situ...
We report the existence of confined electronic states at (110) and (111) surfaces SrTiO3. Using angle-resolved photoemission spectroscopy, we find that corresponding Fermi surfaces, subband masses, orbital ordering are different from ones (001) surface This occurs because crystallographic symmetries sub-surface planes, electron effective masses along confinement direction, influence symmetry structure t2g manifold. Remarkably, our analysis data also reveals carrier concentration thickness...
Abstract The hybridization between localized 4 f electrons and itinerant in rare-earth-based materials gives rise to their exotic properties like valence fluctuations, Kondo behaviour, heavy-fermions, or unconventional superconductivity. Here we present an angle-resolved photoemission spectroscopy (ARPES) study of the lattice antiferromagnet CeRh 2 Si , where surface bulk Ce-4 spectral responses were clearly resolved. pronounced 0 peak seen for Ce terminated gets strongly suppressed spectra...
Two-dimensional electron gases (2DEGs) at transition-metal oxide (TMO) interfaces and boundary states in topological insulators, are being intensively investigated. The former system harbors superconductivity, large magneto-resistance ferromagnetism. In the latter, honeycomb-lattice geometry plus bulk spin-orbit interactions lead to topologically protected spin-polarized bands. 2DEGs TMOs with a honeycomb-like structure could yield new of matter, but they had not been experimentally...
We report the existence of metallic two-dimensional electron gases (2DEGs) at (001) and (101) surfaces bulk-insulating TiO2 anatase due to local chemical doping by oxygen vacancies in near-surface region. Using angle-resolved photoemission spectroscopy, we find that electronic structure both is composed two occupied subbands d_xy orbital character. While Fermi surface observed termination isotropic, 2DEG anisotropic shows a charge carrier density three times larger than surface. Moreover,...
We study the effect of oxygen vacancies on electronic structure model strongly correlated metal SrVO$_3$. By means angle-resolved photoemission (ARPES) synchrotron experiments, we investigate systematic UV dose measured spectra. observe onset a spurious dose-dependent prominent peak at an energy range were lower Hubbard band has been previously reported in this compound, raising questions its previous interpretation. careful analysis dependent effects succeed disentangling contributions...
Two-dimensional electron gases at oxide surfaces or interfaces show exotic ordered states of matter, like superconductivity, magnetism spin-polarized states, and are a promising platform for alternative oxide-based electronics. Here we directly image dense population randomly distributed ferromagnetic domains ∼40 nm typical sizes room temperature the oxygen-deficient surface SrTiO3, non-magnetic transparent insulator in bulk. We use laser-based photoemission microscopy, an experimental...
Cu(In,Ga)S${}_{2}$ is a promising material for multijunction solar cells due to its tunable band gap, but still suffers from low efficiency of unknown origin. The authors study structural, optical, and electrical properties with respect annealing temperature, find that higher temperature reduces the density deep defects, leading open-circuit voltage responsible recently observed improvements in efficiency. This could lead further optimization this material, better design cells.
We create a two-dimensional electron system (2DES) at the interface between EuO, ferromagnetic insulator, and SrTiO3, transparent non-magnetic insulator considered bedrock of oxide-based electronics. This is achieved by controlled in-situ redox reaction pure metallic Eu deposited room temperature on surface an innovative bottom-up approach that can be easily generalized to other functional oxides scaled applications. Additionally, we find resulting EuO capping layer tuned from paramagnetic...
A new technique of high-resolution micro-Raman thermometry using anatase TiO2 microparticles (0.5-3 μm) is presented. These very high spatial resolution measurements (280 nm) reveal temperature gradients even within individual microparticles. Potential applications this are demonstrated by probing the distribution a micro-fabricated heater consisting thin silicon nitride (Si-N) membrane with gold coil on top membrane. Using microparticle thermometry, from outer edge to inner portion was...
We report the existence of a two-dimensional electron system (2DES) at $(001)$ surface ${\mathrm{CaTiO}}_{3}$. Using angle-resolved photoemission spectroscopy, we find hybridization between ${d}_{xz}$ and ${d}_{yz}$ orbitals, not observed in 2DESs surfaces other $A{\mathrm{TiO}}_{3}$ perovskites, e.g., ${\mathrm{SrTiO}}_{3}$ or ${\mathrm{BaTiO}}_{3}$. Based on comparison 2DES properties these three materials, show how electronic structure (bandwidth, orbital energy order, density) is coupled...
It was recently discovered that a conductive, metallic state is formed on the surface of some insulating oxides. First observed ${\mathrm{SrTiO}}_{3}$ (001), it then found in other compounds as diverse anatase ${\mathrm{TiO}}_{2}$, ${\mathrm{KTaO}}_{3}$, ${\mathrm{BaTiO}}_{3}$, ZnO, and also different surfaces (or oxides) with symmetries. The spatial extension wave function this electronic only few atomic layers. Experiments indicate its existence related to presence oxygen vacancies induced...
We realize a two-dimensional electron system (2DES) in ZnO by simply depositing pure aluminum on its surface ultra-high vacuum, and characterize electronic structure using angle-resolved photoemission spectroscopy. The oxidizes into alumina creating oxygen vacancies that dope the bulk conduction band of confine electrons near surface. density 2DES is up to two orders magnitude higher than those obtained heterostructures. shows $s$-type subbands, we compare $d$-like 2DESs titanates, with...
Electronic properties of low dimensional superconductors are determined by many-body-effects. This physics has been studied traditionally with superconducting thin films and in recent times two-dimensional electron gases (2DEGs) at oxide interfaces. In this work, we show that a 2DEG can be generated simply evaporating layer metallic Al under ultrahigh vacuum on SrTiO3 crystal, whereby oxidizes into amorphous insulating alumina, doping the surface oxygen vacancies. The critical temperature...
Abstract. Carbonaceous aerosols are responsible for large uncertainties in climate models, degraded visibility, and adverse health effects. The Aerosols Radiative Effects Study (CARES) was designed to study carbonaceous the natural environment of Central Valley, California, learn more about their atmospheric formation aging. This paper presents results from spectro-microscopic measurements particles collected during CARES at time pollution accumulation event (27–29 June 2010), when situ...
Significance The transition of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">U</mml:mi> mathvariant="normal">R</mml:mi> mathvariant="normal">u</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> mathvariant="normal">S</mml:mi> mathvariant="normal">i</mml:mi> </mml:math> to an ordered state below 17.5 K has been a puzzle condensed matter physics for over 30 y, earning it the soubriquet hidden-order (HO) state....