A5037942334- Graphene research and applications
- Quantum and electron transport phenomena
- Plasmonic and Surface Plasmon Research
- 2D Materials and Applications
- Photonic and Optical Devices
- Topological Materials and Phenomena
- Metamaterials and Metasurfaces Applications
- Diamond and Carbon-based Materials Research
- Nanowire Synthesis and Applications
- Perovskite Materials and Applications
- Molecular Junctions and Nanostructures
- Silicon Nanostructures and Photoluminescence
- Quantum Dots Synthesis And Properties
- Chalcogenide Semiconductor Thin Films
- Electronic and Structural Properties of Oxides
- Thermal Radiation and Cooling Technologies
- Physics of Superconductivity and Magnetism
- Photonic Crystals and Applications
- Mechanical and Optical Resonators
- Magnetic and transport properties of perovskites and related materials
- Advancements in Battery Materials
- Semiconductor Quantum Structures and Devices
- Semiconductor materials and devices
- Orbital Angular Momentum in Optics
- GaN-based semiconductor devices and materials
Centre National pour la Recherche Scientifique et Technique (CNRST)
2025
Centre d’Élaboration de Matériaux et d’Études Structurales
2020-2024
Université de Toulouse
2009-2024
Centre National de la Recherche Scientifique
2009-2024
University of Geneva
2016-2021
Université Toulouse III - Paul Sabatier
2009-2020
École Polytechnique Fédérale de Lausanne
2016
National High Magnetic Field Laboratory
2009-2015
Florida State University
2014-2015
Institut National des Sciences Appliquées de Toulouse
2011
Although the main Raman features of semiconducting transition metal dichalcogenides are well known for monolayer and bulk, there important differences exhibited by few layered systems which have not been fully addressed. WSe2 samples were synthesized ab-initio calculations carried out. We calculated phonon dispersions Raman-active modes in systems: WSe2, MoSe2, WS2 MoS2 ranging from monolayers to five-layers bulk. First, we confirmed that as number layers increase, E′, E″ E2g shift lower...
Abstract Isolators, or optical diodes, are devices enabling unidirectional light propagation by using non-reciprocal materials, namely materials able to break Lorentz reciprocity. The realization of isolators at terahertz frequencies is a very important open challenge made difficult the intrinsically lossy radiation in current materials. Here we report design, fabrication and measurement isolator for circularly polarized waves based on magnetostatically biased monolayer graphene, operating...
Abstract Here, we present a temperature ( T ) dependent comparison between field-effect and Hall mobilities in transistors based on few-layered WSe 2 exfoliated onto SiO . Without dielectric engineering beyond -dependent threshold gate-voltage, observe maximum hole approaching 350 cm /Vs at = 300 K. The mobility reaches value of 650 as is lowered below ~150 K, indicating that insofar -based (FETs) display the largest among transition metal dichalcogenides. gate capacitance, extracted from...
Abstract The magnetic circular dichroism and the Faraday rotation are fundamental phenomena of great practical importance arising from breaking time reversal symmetry by a field. In most materials, strength sign these effects can be only controlled field value its orientation. Furthermore, terahertz range is lacking materials having ability to affect polarization state light in non-reciprocal manner. Here we demonstrate, using broadband magneto-electro-optical spectroscopy, that graphene...
The Integer Quantum Hall Effect (IQHE) is a distinctive phase of two-dimensional electronic systems subjected to perpendicular magnetic field. Thus far, the IQHE has been observed in semiconductor heterostructures and mono- bi-layer graphene. Here we report on new system: trilayer Experimental data are compared with self-consistent Hartree calculations Landau levels for gated trilayer. plateau structure resistivity determines stacking order (ABA versus ABC). We find that ABC graphene similar...
Abstract We report the influence on superconducting critical temperature T c in doped SrTiO 3 of substitution natural 16 O atoms by heavier isotope 18 O. observe that for a wide range doping this causes strong (~50%) enhancement . Also magnetic field H 2 is increased factor ~2. Such impact and , with sign opposite to conventional superconductors, unprecedented. The observed effect could be consequence coupling electrons lattice vibrations (phonons), notion which finds support numerous...
We report on (magneto)transport experiments in chemically derived narrow graphene nanoribbons under high magnetic fields (up to 60 T). Evidences of field-dependent electronic confinement are given and allow estimating the possible ribbon edge symmetry. A large positive magnetoconductance indicates a strong suppression backscattering induced by field. Such scenario is supported tight-binding calculations which consider different types underlying disorders (smooth disorder long-range Coulomb...
Magnetotransport measurements are performed in ultraclean (lithographically patterned) graphene nanoribbons down to 70 nm. At high magnetic fields, a fragmentation of the electronic spectrum into Landau levels pattern with unusual features is unveiled. The singular reveals large magneto-oscillations Fermi energy and valley degeneracy lifting. Quantum simulations suggest some disorder threshold at origin mixing between opposite chiral edge states disappearance quantum Hall effect.
Abstract This study investigates the mechanisms underlying colour production in family Coccinellidae, focusing on two model species: A. bipunctata (L) and C. quatuordecimguttata . In this family, colours have traditionally been attributed primarily to pigments such as carotenoids melanins. We propose an alternative perspective, considering elytra integrated optical medium whose properties result from both its architectural design of constituent materials, including matrix pigments. present...
Abstract Chemical vapor deposition (CVD) allows lateral edge epitaxy of transition metal dichalcogenide heterostructures. Critical for carrier and exciton transport is the material quality nature heterojunction. Important details optical properties were inaccessible in as-grown heterostructure samples due to large inhomogeneous broadening transitions. Here we perform spectroscopy CVD grown MoSe 2 -WSe heterostructures, encapsulated hBN. Photoluminescence (PL), reflectance contrast Raman...
We present an infrared transmission spectroscopy study of the inter-Landau-level excitations in quasineutral epitaxial graphene nanoribbon arrays. observed a substantial deviation energy L(0(-1)) → L(1(0)) transition from characteristic square root magnetic-field dependence two-dimensional graphene. This arises formation upper-hybrid mode between Landau-level and plasmon resonance. In quantum regime, hybrid exhibits distinct dispersion relation, markedly different that expected for...
We report on cyclotron effective mass measurement in indium nitride epilayers grown c-sapphire, using the thermal damping of Shubnikov-de-Haas oscillations obtained temperature range 2–70 K and under magnetic field up to 60 T. unravel an isotropic electron equal 0.062±0.002m0 for samples having concentration near 1018 cm−3. After nonparabolicity polaron corrections we estimate a bare at bottom band 0.055±0.002m0.
Faraday rotation is a fundamental property present in all non-reciprocal optical elements. In the THz range, graphene displays strong rotation; unfortunately, it limited to frequencies below cyclotron resonance. Here we show experimentally that specifically design metasurfaces, magneto-plasmons can be used circumvent this limitation. We find excellent agreement between theory and experiment provide new physical insights predictions on these phenomena. Finally, demonstrate tuneability...
We show how to prepare graphene samples on a glass substrate with the anodic bonding method. In this method, graphite precursor in flake form is bonded help of an electrostatic field and then cleaved off leave few layer substrate. Now that several methods are available for producing graphene, relevance our method its simplicity practicality about 100 µm lateral dimensions. This also extensible other layered materials. discuss some detailed aspects fabrication results from Raman spectroscopy,...
We perform polarization-resolved Raman spectroscopy on graphene in magnetic fields up to 45T. This reveals a filling-factor-dependent, multi-component anticrossing structure of the G peak, resulting from magnetophonon resonances between magnetoexcitons and E$_{2g}$ phonons. is explained with model scattering taking into account effects spatially inhomogeneous carrier densities strain. Random fluctuations strain-induced pseudo-magnetic lead increased intensity inside anti-crossing gap,...
We report on Landau level spectroscopy studies of two HgTe quantum wells (QWs) near or at the critical well thickness, where band gap vanishes. In magnetic fields up to $B=16$ T, oriented perpendicular QW plane, we observe a $\sqrt{B}$ dependence for energy dominant cyclotron resonance (CR) transition characteristic two-dimensional Dirac fermions. The CR line exhibits either single double absorption shape gapless gapped QW. Using an effective model, deduce velocity single-valley fermions in...
We present the experimental realization of ordered arrays hyper-doped silicon nanodisks, which exhibit a localized surface plasmon resonance. The is widely tunable in spectral window between 2 and 5 μm by adjusting free carrier concentration 1020 1021 cm–3. show that strong infrared light absorption can be achieved with all-silicon plasmonic metasurfaces employing nanostructures dimensions as low 100 nm diameter 23 height. Our numerical simulations an excellent agreement data provide...
We optimize silicon nano-antennas to enhance and direct the emission of local quantum sources. combine global evolutionary optimization (EO) with frequency domain electrodynamical simulations compare design strategies based on resonant non-resonant building blocks. Specifically, we investigate performance models different degrees freedom but comparable amounts available material. find that simpler geometric allow significantly faster convergence optimizer, which, expectedly, comes at cost a...
We report on oscillatory magnetoabsorption experiments several indium nitride (InN) epilayers under a pulsed magnetic field up to 56 T. This optical technique is uniquely suited probe the bulk electronic structure in vicinity of fundamental band edge by Landau level spectroscopy. discuss these results light two recent studies InN high-field magnetotransport [Goiran et al., Appl. Phys. Lett. 96, 052117 (2010)] and magneto-photoluminescence [Pettinari Rev. B 79, 165207 (2009)]. In particular,...
Abstract Optical Mie resonators based on silicon nanostructures allow tuning of light-matter-interaction with advanced design concepts complementary metal–oxide–semiconductor (CMOS) compatible nanofabrication. Optically active materials such as transition-metal dichalcogenide (TMD) monolayers can be placed in the near-field region resonators. Here, we experimentally demonstrate and verify by numerical simulations coupling between a MoSe 2 monolayer dielectric nanoresonators. Through...
Being able to control the neutral excitonic flux is a mandatory step for development of future room-temperature two-dimensional devices. Semiconducting Monolayer Transition Metal Dichalcogenides (TMD-ML) with extremely robust and mobile excitons are highly attractive in this regard. However, generating an efficient controlled exciton transport over long distances very challenging task. Here we demonstrate that atomically sharp TMD-ML lateral heterostructure (MoSe$_{2}$-WSe$_{2}$) transforms...
Light emission of europium (Eu3+) ions placed in the vicinity optically resonant nanoantennas is usually controlled by tailoring local density photon states (LDOS). We show that polarization and shape excitation beam can also be used to manipulate light emission, as azimuthally or radially polarized cylindrical vector offers spatially electric magnetic fields, addition effect silicon nanorings (Si-NRs) nanoantennas. The photoluminescence mappings Eu3+ transitions Si phonon are strongly...
Monolayers (MLs) of transition metal dichalcogenides (TMDs) such as WSe2 and MoSe2 can be placed by dry stamping directly on broadband dielectric resonators, which have the ability to enhance spontaneous emission rate brightness solid-state emitters at room temperature. We show strongly enhanced directivity modifications in room-temperature photoluminescence mapping experiments. By varying TMD material (WSe2 vs MoSe2) transferred silicon nanoresonators with various designs (planarized...
We investigate the quantum Hall regime in a graphene flake with different levels of disorder. Under high magnetic field, an unexpected decrease resistance occurs when only zeroth-energy Landau level is populated. The presence disorder rules out expected appearance $\ensuremath{\nu}=0$ plateau as case pristine graphene. Instead, we propose alternative explanation based on coexistence two types carriers, electrons and holes, induced by