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-00551452] Vortex polarity in 2-D magnetic dots by Langevin dynamics simulations

Date: 15 jan 2022 - 03:44

Desc: [...]

[hal-01243122] Temperature and vortex gyrotropic motion in 2-D magnetic nanodots by Langevin simulations

Date: 15 jan 2022 - 03:44

Desc: Vortex gyrotropic motion was simulated in two-dimensional square magnetic dots of three-dimensional spin vectors of nanometric size. The Landau-Lifshitz equation with exchange and dipolar interactions was integrated at different temperatures with initial conditions consisting in a single vortex shifted aside from the central position. The gyrotropic frequency is computed. The experimental observation that this frequency decreases as temperature is increased is confirmed: we suggest that the reason is the thermal dependence of the damping coefficient in Thiele's equation. Pinning of the vortex-core motion by the underlying lattice is also observed. (C) 2012 Elsevier B.V. All rights reserved.

[hal-01275503] Three-dimensional THz lumped-circuit resonators

Date: 15 jan 2022 - 03:44

Desc: Our work describes a novel three dimensional meta-material resonator design for optoelectronic applications in the THz spectral range. In our resonant circuits, the capacitors are formed by double-metal regions cladding a dielectric core. Unlike conventional planar metamaterials, the electric field is perpendicular to the surface and totally confined in the dielectric core. Furthermore, the magnetic field, confined in the inductive part, is parallel to the electric field, ruling out coupling through propagation effects. Our geometry thus combines the benefit of double-metal structures that provide parallel plate capacitors, while maintaining the ability of meta-material resonators to adjust independently the capacitive and inductive parts. Furthermore, in our geometry, a constant bias can be applied across the dielectric, making these resonators very suitable for applications such as ultra-low dark current THz quantum detectors and amplifiers based on quantum cascade gain medium.

[hal-00777895] Combining moiré patterns and high resolution transmission electron microscopy for in-plane thin films thickness determination

Date: 15 jan 2022 - 03:44

Desc: This paper reports the coupling of HRTEM and moiré pattern observations, allowing the détermination of the thickness ratio of two superimposed crystals. Pseudo-lattice fringes are observed using identical TEM expérimental conditions as for observing moiré patterns. The pseudo-lattice spacing is first calculated in the dynamical theory Framework in two beam conditions. This approach shows a linear behavior of the spacing as a function of the thickness ratio of the two crystals. The rôles of sample crystallographic orientation and sample thickness on the thickness ratio détermination are discussed from multi-beam simulations. Finally, the method is applied on a bimetallic Cu Ag core-shell nanoparticle of a known structure. It is demonstrated that for this particle, the thickness ratio of Cu and Ag can be determined with an error that results in a précision less than 0.75nm on the Cu and Ag thicknesses. The advantages of the technique are the use of an in-plane sample configuration and a single HRTEM image

[hal-01243111] Vortex polarization dynamics in a square magnetic nanodot

Date: 15 jan 2022 - 03:44

Desc: Langevin simulations at finite temperature of two-dimensional magnetic nanodots were performed using the Landau-Lifshitz equation with exchange and dipolar interactions. In a wide range of temperatures, the dynamics of square samples with one central vortex was studied, focusing on the out-of-plane magnetic component at the vortex-core. This vortex-core undergoes polarization sign reversals in a thermally activated process. In the intervals between polarization flips, the out-of-plane spin components at the vortex-core show oscillations with identifiable frequencies connected with certain eigenfrequencies of the system associated with polarity active modes. The vortex-core positions were also monitored.