Laboratoire Pierre Aigrain
Présentation
Le Laboratoire Pierre Aigrain (LPA) est concerné par divers aspects fondamentaux de la nano-physique : boîtes quantiques et microcavités de semiconducteurs, structures conductrices mésoscopiques, films minces supraconducteurs, molécules uniques carbonées (nanotubes) ou biologiques (ADN). Il étudie d’un point de vue expérimental et théorique ces nano-objets dont les possibilités d’application couvrent des domaines aussi diversifiés que l’optoélectronique, l’information quantique, l’électronique moléculaire, la reconnaissance électronique des molécules biologiques. Il travaille en particulier grâce à un réseau de collaborations nationales et internationales (CNRS/CRHEA Valbonne, CEA/CNRS Grenoble, CEA/Saclay, Universités d’Orsay, de Tokyo, de Californie à Santa Barbara, Institut Pasteur, Département de biologie de l’ENS, Max-Planck Institüt, LCR-Thalès, Alcatel, Motorola), sans oublier son partenaire privilégié, le Laboratoire de Photonique et Nanostructures de Marcoussis.
Les techniques expérimentales sont celles de la spectroscopie optique classique ou laser, linéaire ou non linéaire, des mesures de transport électrique en régime continu ou radiofréquence, des mesures de force à l’échelle du piconewton. S’y ajoute une importante activité théorique.
Le Laboratoire compte une soixantaine de personnes: chercheurs, enseignant-chercheurs, ingénieurs et techniciens, doctorants, post-doctorants. Il est divisé en six équipes expérimentales auxquelles s’ajoutent l’équipe théorique, une équipe d'instrumentation et un service administratif. Il participe activement aux activités d'enseignement de l'ENS et des universités Paris Diderot et Paris 6.
Jean-Marc Berroir
Thèmes de recherche
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Biophysique
- Physique du vivant : Moteurs moléculaires et interactions ADN-protéines à l'échelle de la molécule unique: mesures de force par piège optique et pince magnétique
- Physique de l'ADN : Approches physiques de la biologie moléculaire: manipulation de molécules uniques, mesures de force par pièges optiques et mesures électroniques
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Propriété électronique des nano-objets
- Optique cohérente et non-linéaire : Nouveaux Matériaux et microcavités, Propriétés opto-électroniques des hétérostructures
- Infra-rouge lointain : Magnétospectroscopie des nanostructures dans l'infrarouge lointain
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Théorie
- Propriétés électroniques des nano-objets
- Systèmes fortement corrélés et mésoscopiques : effet Hall quantique fractionnaire, liquides de Luttinger, magnétisme en basses dimensions
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Physique Mésoscopique - Transport
- Physique Mésoscopique : transport mésoscopique hyperfréquence, transport électronique à l'échelle atomique
- Transport : Dynamique du paramètre d'ordre supraconducteur et des vortex
[cea-01630881] Davydov splitting and self-organization in a porphyrin layer noncovalently attached to Single wall carbon nanotubes
Date: 8 oct 2021 - 12:00
Desc: We study the ability of porphyrin molecules to cooperate upon adsorption on the sp2 curved surface of carbon nanotube. We discuss the role of the phenyl substituents in the cooperativity of the functionalization reaction. Moreover, a specific spatial organization of the molecules around the nanotube is unveiled through polarization sensitive experiments. Furthermore, we observe an increase of the energy splitting of the porphyrin main transition upon the adsorption on the nanotube. This effect, interpreted as a Davydov splitting, is analyzed quantitatively using a dipole–dipole coupling model. This study demonstrates the ability of porphyrin molecules to create an organized self-assembled layer at the surface of the nanotubes where molecules are electronically coupled together.
[cea-01414729] Thermodynamics study of the noncovalent functionalization of surfactant suspended graphene nanosheets with porphyrin molecules
Date: 8 oct 2021 - 11:58
Desc: We report on the noncovalent functionalization of graphene with hydrophobic tetraphenyl porphyrin (TPP) molecules in micellar aqueous suspensions. We study the thermodynamical parameters of the reaction using optical spectroscopy, and measure its Gibbs energy. We show that a total reaction can be achieved, leading to a high functionalization yield, despite the $\pi$-stacking noncovalent binding
[cea-01470484] Controlling the kinetics of the non-covalent functionalization of carbon nanotubes using sub-cmc dilutions in a co-surfactant environment †
Date: 8 oct 2021 - 12:03
Desc: We investigate the origin of the slow kinetics of functionalization processes in micellar environments. We show that the ionic nature of the surfactants used to solubilize small molecules and nano-objects plays a central role in the slowness of the kinetics. In order to solve this issue, we have developed an innovative method that we apply to the hybrid compound porphyrin molecule/carbon nanotube. We use two ionic surfactants to solubilize the molecules and the nanotubes respectively. Passing the molecule suspension below the cmc allows circumventing the stability of the ionic surfactant while keeping the benefit of working with highly concentrated solutions. This method allows fine control of the functionalization reaction and tuning of the kinetics characteristic time over more than two orders of magnitude.
[hal-00533111] Superconducting nanowire single electron detector
Date: 5 nov 2010 - 11:22
Desc: WE REPORT THE DETECTION OF SINGLE ELECTRONS USING A 6 NM-THICK, 100 NM-WIDE, NB0.7TI0.3N SUPERCONDUCTING STRIP DEPOSITED ON A SIOX/SI SUBSTRATE. WHEN BIASED SLIGHTLY BELOW THE CRITICAL CURRENT, A MEANDER-SHAPED DEVICE, NOT ONLY DETECTS SINGLE PHOTONS, BUT ALSO COUNTS THE SINGLE KEV ELECTRONS ISSUED FROM A SCANNING ELECTRON MICROSCOPE (SEM) WITH AN EFFICIENCY APPROACHING UNITY. THE RESPONSE TIME IS SHORT ENOUGH TO DISCRIMINATE THE INCIDENT ELECTRONS FROM THOSE BACKSCATTERED FROM THE UNDERLYING MATERIAL. IT IS THEREFORE POSSIBLE TO MAP THE ELECTRON DETECTIVITY AS WELL AS THE PHOTON DETECTIVITY ON THE SAME DEVICE. A CLEAR CORRELATION BETWEEN THE TWO MEASUREMENTS IS OBSERVED, WITH A SUPERIOR SPATIAL RESOLUTION THOUGH (AROUND 100 NM) FOR THE SEM MAPPING. IT ILLUSTRATES THE POTENTIAL USE OF THIS SINGLE ELECTRON MAPPING BY THE SEM METHOD TO CHARACTERIZE THE DETECTION HOMOGENEITY OF SSPDS
[hal-00436122] Spin-dependent boundary conditions for isotropic superconducting Green's functions
Date: 26 nov 2009 - 10:40
Desc: The quasiclassical theory of superconductivity provides the most successful description of diffusive heterostructures comprising superconducting elements, namely, the Usadel equations for isotropic Green's functions. Since the quasiclassical and isotropic approximations break down close to interfaces, the Usadel equations have to be supplemented with boundary conditions for isotropic Green's functions (BCIGF), which are not derivable within the quasiclassical description. For a long time, the BCIGF were available only for spin-degenerate tunnel contacts, which posed a serious limitation on the applicability of the Usadel description to modern structures containing ferromagnetic elements. In this article, we close this gap and derive spin-dependent BCIGF for a contact encompassing superconducting and ferromagnetic correlations. This finally justifies several simplified versions of the spin-dependent BCIGF, which have been used in the literature so far. In the general case, our BCIGF are valid as soon as the quasiclassical isotropic approximation can be performed. However, their use require the knowledge of the full scattering matrix of the contact, an information usually not available for realistic interfaces. In the case of a weakly polarized tunnel interface, the BCIGF can be expressed in terms of a few parameters, i.e. the tunnel conductance of the interface and five conductance-like parameters accounting for the spin-dependence of the interface scattering amplitudes. In the case of a contact with a ferromagnetic insulator, it is possible to find explicit BCIGF also for stronger polarizations. The BCIGF derived in this article are sufficienly general to describe a variety of physical situations and may serve as a basis for modelling realistic nanostructures.
Autres contacts
Ecole Normale Supérieure (Paris-Ulm)
Bâtiment de Physique
1er étage - pièces D17-D13
24, rue Lhomond
75205 PARIS CEDEX 13