Matériaux et Phénomènes Quantiques

MPQ

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Université Paris Diderot

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UFR Physique

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Présentation

Le laboratoire Matériaux et Phénomènes Quantiques (MPQ) est une unité mixte de recherche (UMR 7162) du CNRS et de l’Université Paris Diderot, installée sur le campus de Paris Rive Gauche. Elle est composée d’environ 120 personnes au total dont 51 permanent.e.s.

Le laboratoire est spécialisé dans l’étude des matériaux quantiques de frontière et dans le développement de dispositifs quantiques innovants. Ces activités reposent sur un large spectre de compétences théoriques et expérimentales alliant la physique des matériaux, le transport et l’optique, et des plateformes technologiques de salle blanche, de spectroscopie et de microscopie électronique haute résolution.

Les activités de recherche du laboratoire MPQ se déclinent selon les thèmes suivants :

nouveaux matériaux à l’échelle nano : nanoparticules, nanocristaux, nanotubes fonctionnalisés, matériaux multiferroïques, etc.
nouveaux états de la matière : fluides quantiques de lumière, couplage ultra-fort en cavité, supraconducteurs non-conventionnels, systèmes fortement corrélés, phases topologiques, etc.
systèmes nano-optiques innovants : optomécanique, nanophotonique non-linéaire, nanoplasmonique, etc.
ingénierie quantique et information quantique : composants optoélectroniques quantiques, circuits photoniques quantiques, ions piégés, matériaux et composants hybrides organique/inorganique, ingénierie des surfaces/interfaces.

Les projets actuels du laboratoire incluent le développement de nouvelles sondes pour l’étude des matériaux quantiques, comme la spectroscopie Raman résolue en temps, la microscopie AFM opto-mécanique et la microscopie tunnel sous excitation optique. Réciproquement, les matériaux de frontière sont mis à profit pour la réalisation de nouvelles fonctionnalités dans des senseurs optomécaniques, des circuits photoniques non-linéaires et quantiques, ou encore dans des expériences de transport mésoscopique en cavité optique.

[hal-01441517] Structural Properties of Double-Walled Carbon Nanotubes driven by Mechanical Interlayer Coupling.

Date: 25 juil 2021 - 20:20

Desc: Structural identification of double-walled carbon nanotubes (DWNT) is presented through a robust procedure based on the latest generation of transmission electron microscope, making possible a statistical analysis based on numerous nano-objects. This approach reveals that inner and outer tubes of DWNTs are not randomly oriented, suggesting the existence of a mechanical coupling between the two concentric walls. With the support of atomic scale modelisations, we attribute it to the presence of incommensurate domains whose structures depend on the diameters and helicities of both tubes, and where inner tubes try to achieve a local stacking orientation to reduce strain effects.

[hal-01993925] Structural properties of Double Wall Carbon Nanotubes as revealed by TEM

Date: 25 juil 2021 - 20:20

Desc: Single wall carbon nanotubes (SWCNTs) and 2D materials are new classes of materials, which can be considered as isolated nano-objects or can be assembled together to get multifunctional heterostructures. A key question is how components of such hybrid structures interact together, whether their properties are coupled or not and the possible impact on their respective properties. In line with this, SWCNTs have exhibited, since their discovery [1], extraordinary properties but also an extreme sensitivity to any slight fluctuation in their environment. This difficulty could be solved by employing double wall nanotubes (DWCNT), where the outer layer is assigned to play a protecting role with respect to the inner layer. However, the interaction between the layers requires to be known in detail. To that respect, DWCNT represent the ideal and simpliest case to investigate the nature of the interaction between two walls within a multiwall nanotube. This is the purpose of the study we have undertaken. DWCNT are produced using a CVD technique described in [2] and serve as long standing reference samples in numerous studies. Structural identification of the nanotubes is presented through a robust procedure based on the use of a Cs-corrected JEOL ARM200 operating at 80kV, making possible the recording of HRTEM phase contrast images with an atomic resolution and a statistical analysis based on the inspection of numerous nano-objects. Figure 1 shows a typical HRTEM image, which displays a complex moiré pattern that arises from the projected view of four rotated hexagonal networks. In order to achieve a fully atomic-resolved structure reconstruction from such an image, we defined a data processing sequence composed of different steps detailed in [3] and summarized in Figure 2. A complete structure identification is provided by the determination of respective diameters and helicity angles of both outer and inner tubes. Diameters are determined from the intensity profiles related to the set of dark/bright fringes lying on each side of the tube images. Helicities are extracted from the numerical fast Fourier transform (FFT) of the image, which is analysed as a diffraction pattern according to the procedure developed in [4]. Final step consists in defining the atomic structures of both inner and outer tubes fitting at the best diameters and helicities and leading to the best matching simulations of both HRTEM images and its FFT. This approach reveals that inner and outer tubes of DWNTs are not randomly oriented, suggesting the existence of a mechanical coupling between the two concentric walls (Figure 3). Furthermore, we frequently observe that the inner tube is locally defective whereas the outer remains perfect. With the support of atomic-scale modeling (DFT calculations), we attribute it to the presence of incommensurate domains which structures depend on the diameters and helicities of both tubes and where inner tubes try to achieve a local stacking orientation to reduce strain effects [3]. Furthermore Monte Carlo (MC) simulations have confirmed that experimentally forbidden DWCNT are unstable and that the unstability results in structure modification of the inner layer as experimentally observed [3] (Figure 3).

[hal-01687177] Structural Properties of Double-Walled Carbon Nanotubes Driven by Mechanical Interlayer Coupling

Date: 25 juil 2021 - 20:20

Desc: Structural identification of double-walled carbon nanotubes (DWNTs) is presented through a robust procedure based on the latest generation of transmission electron microscope, making possible a statistical analysis based on numerous nanoobjects. This approach reveals that inner and outer tubes of DWNTs are not randomly oriented, suggesting the existence of a mechanical coupling between the two concentric walls. With the support of atomic-scale modeling, we attribute it to the presence of incommensurate domains whose structures depend on the diameters and helicities of both tubes and where inner tubes try to achieve a local stacking orientation to reduce strain effects

[ineris-00963273] Long term in vivo biotransformation of iron oxide nanoparticles

Date: 23 juil 2021 - 04:54

Desc: The long term outcome of nanoparticles in the organism is one of the most important concerns raised by the development of nanotechnology and nanomedicine. Little is known on the way taken by cells to process and degrade nanoparticles over time. In this context, iron oxide superparamagnetic nanoparticles benefit from a privileged status, because they show a very good tolerance profile, allowing their clinical use for MRI diagnosis. It is generally assumed that the specialized metabolism which regulates iron in the organism can also handle iron oxide nanoparticles. However the biotransformation of iron oxide nanoparticles is still not elucidated. Here we propose a multiscale approach to study the fate of nanomagnets in the organism. Ferromagnetic resonance and SQUID magnetization measurements are used to quantify iron oxide nanoparticles and follow the evolution of their magnetic properties. A nanoscale structural analysis by electron microscopy complements the magnetic follow-up of nanoparticles injected to mice. We evidence the biotransformation of superparamagnetic maghemite nanoparticles into poorly-magnetic iron species probably stored into ferritin proteins over a period of three months. A putative mechanism is proposed for the biotransformation of iron-oxide nanoparticles