BEGIN:VCALENDAR VERSION:2.0 PRODID:-//FeRMI - ECPv6.15.20//NONSGML v1.0//EN CALSCALE:GREGORIAN METHOD:PUBLISH X-ORIGINAL-URL:https://fermi.univ-tlse3.fr X-WR-CALDESC:Évènements pour FeRMI REFRESH-INTERVAL;VALUE=DURATION:PT1H X-Robots-Tag:noindex X-PUBLISHED-TTL:PT1H BEGIN:VTIMEZONE TZID:Europe/Paris BEGIN:DAYLIGHT TZOFFSETFROM:+0100 TZOFFSETTO:+0200 TZNAME:CEST DTSTART:20230326T010000 END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:+0200 TZOFFSETTO:+0100 TZNAME:CET DTSTART:20231029T010000 END:STANDARD BEGIN:DAYLIGHT TZOFFSETFROM:+0100 TZOFFSETTO:+0200 TZNAME:CEST DTSTART:20240331T010000 END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:+0200 TZOFFSETTO:+0100 TZNAME:CET DTSTART:20241027T010000 END:STANDARD BEGIN:DAYLIGHT TZOFFSETFROM:+0100 TZOFFSETTO:+0200 TZNAME:CEST DTSTART:20250330T010000 END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:+0200 TZOFFSETTO:+0100 TZNAME:CET DTSTART:20251026T010000 END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20240905T140000 DTEND;TZID=Europe/Paris:20240905T153000 DTSTAMP:20260418T084202 CREATED:20240828T065637Z LAST-MODIFIED:20240902T071424Z UID:10904-1725544800-1725550200@fermi.univ-tlse3.fr SUMMARY:Real-time time-dependent density functional theory for nanoplasmonics : Neutral and charged nanowire dimers. - (Lorenzo Stella / LPT / Seminar). - 5/09/2024\, 14H DESCRIPTION:Lorenzo Stella (Université Queen’s de Belfast) \nSeminar LPT\, 5/09/2024\, 14H\, 3R1\, seminar room\, 3rd floor \nAbstract :  \nPlasmons are electron density oscillations with respect to the ionic background. Metal and heavily doped semiconductors can support volume\, surface and localised plasmon modes. In plasmonic devices\, plasmonic modes are used\, e.g.\, for chemical sensing\, promoting catalysis and localised heating. Numerical modelling of plasmonic devices is routinely done by solving macroscopic Maxwell equations\, given a suitable parametrisation of the material (metal and dielectric) permittivities. \nAt the nanoscale\, numerical models based on macroscopic permittivities are no longer reliable. At this scale\, time-dependent density functional theory (TDDFT) within the adiabatic local density approximation (ALDA) already provides a reliable description of the electron density oscillations\, including subtle effects due to electron spill-out and tunnelling. \nIn this talk\, I will illustrate the application of TDDFT to nanoplasmonics using a nanowire dimer as a test-case. Well-known results for the plasmon resonance evolution of neutral dimers as a function of the nanowire distance will be compared with more recent results for their charged counterparts. Our real-time TDDFT results suggest that oppositely charged nanowires form a « nanocapacitor » which can « discharge » by means of a charge-transfer current through the gap. \n  URL:https://fermi.univ-tlse3.fr/event/tba-lorenzo-stella-lpt-seminar-5-09-2024-14h/ LOCATION:salle de séminaire 3ème étage\, Bâtiment 3r1 Université Toulouse III\, Toulouse\, 31400\, France CATEGORIES:Events,LPT,Seminars END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20240906T110000 DTEND;TZID=Europe/Paris:20240906T123000 DTSTAMP:20260418T084202 CREATED:20240827T082334Z LAST-MODIFIED:20240902T071117Z UID:10921-1725620400-1725625800@fermi.univ-tlse3.fr SUMMARY:L’étude de nano matériaux pour l’élaboration de nano capteurs optiques. Application à la détection de fuites d’hydrogène. - (Nicolas Javahiraly / FeRMI / Séminaire). - 6/09/2024\, 11H DESCRIPTION:Séminaires d’ouverture FeRMI\n \nNicolas Javahiraly\, Laboratoire de bioélectrochimie et spectroscopie – Strasbourg \nAbstract :\nVecteur d’énergie\, l’hydrogène est actuellement utilisé dans diverses industries chimiques\, pharmaceutiques\, aérospatiales. Dans le contexte de transition énergétique actuel\, son utilisation n’est que grandissante dans les applications de production\, de stockage ou de distribution. L’industrie reposant sur l’utilisation de l’hydrogène gazeux rencontre des problèmes de sécurité dus aux propriétés chimiques et physiques de ce gaz (inflammabilité) d’où la nécessité d’élaborer de nouveaux systèmes de nano-détection ultrarapides et sensibles. \nDe nouvelles configurations de capteurs originaux ont été proposées : par exemple\, un capteur SPR (Surface Plasmon Resonance) fibré à modulation de longueur d’onde utilisant des nanocouches de Pd comme matériau sensible à la détection du gaz. La zone sensible\, déposée sur le cœur d’une fibre multimode\, peut être par exemple\, une configuration MIM (Metal/Insulator/Metal) multicouches d’argent\, de silice et de palladium. La modulation spectrale de la lumière transmise par la fibre\, basée sur un changement de permittivité\, permet la détection de l’hydrogène. Une réponse plus fiable est alors envisagée pour ce capteur SPR basé sur une modulation spectrale plutôt qu’en intensité. Les épaisseurs des différentes couches définissent alors les performances du capteur. Une configuration optimale a alors été obtenue et nous a laissé entrevoir un futur prometteur\, notamment via des systèmes à base de nanoparticules et de nanostructures originales. \nD’autres types de capteurs utilisant des nanoparticules et/ou des réseaux de nanoparticules de différentes formes offrent également des performances tout à fait compétitives au regard des normes et des spécifications strictes dans diverses industries impliquées dans l’économie de l’hydrogène. Se pose alors la question de la faisabilité de nouveaux détecteurs ultrasensibles et très réactifs à base de nanoobjets originaux qui nous ont incité à entreprendre des études in situ à l’échelle nano-et subnanométrique\, afin de mieux comprendre les mécanismes mis en jeu lors de ces processus de détection URL:https://fermi.univ-tlse3.fr/event/nanomateriaux-et-hydrogene-nicolas-javahiraly-seminaire-fermi-16-09-2024-11h/ LOCATION:Salle de conférence\, Bâtiment 3R4 CATEGORIES:Events,FeRMIsem,Seminars END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20240910T110000 DTEND;TZID=Europe/Paris:20240910T123000 DTSTAMP:20260418T084202 CREATED:20240825T133906Z LAST-MODIFIED:20240829T082324Z UID:10941-1725966000-1725971400@fermi.univ-tlse3.fr SUMMARY:Reviving Old Theories with 2D Materials. - (Ji Ung Lee/ Seminar / CEMES). - 10/09/2024\, 11H DESCRIPTION:Séminaire invité FERMI\n \nséminaire organisé par W Bacsa \nJi Ung Lee\, College of Nanotechnology\, Science\, and Engineering\, SUNY-Albany\, Albany\, NY. \nSummary:\nI will describe our efforts to revisit three theoretical concepts that are best demonstrated in 2D van der Waals (vdW) materials. Specifically\, I will describe experimental realizations of\, or our attempt to verify\, these theories that were predicted decades ago using novel devices. \nIn the first part of my talk\, I will describe the counterintuitive transmission of relativistic particles through a potential barrier\, known as the Klein paradox. Here\, the particles or quasiparticles are electrons that exhibit light‐like (photon‐like) characteristics in graphene. When these carriers impinge on a barrier\, they transmit as if the barrier is not present. Nonrelativistic particles\, such as electrons in a normal semiconductor\, do not behave this way. Klein predicted these properties in the early days of quantum mechanics using the Dirac equation. The discovery of graphene has allowed us to demonstrate the Klein paradox in a condensed matter system. \nIn the second part of my talk\, I will discuss Schottky barriers. A Schottky barrier forms at a metal‐semiconductor interface and is one of the fundamental devices in semiconductor technology. Ideally\, the metal work function determines the barrier height\, known as the Schottky‐Mott limit. This ideal description has been taught for decades\, even though it had not been realized experimentally ‐ until recently. Typically\, defect states form at the interface\, which pin the metal Femi level. I will describe a Schottky junction formed at a vdW interface that obeys the Schottky‐Mott rule. \nFinally\, I will describe our efforts to find Majorana zero modes (Majorana fermions). A Majorana particle is its own antiparticle. I will discuss our use of EUV patterning techniques to accomplish this. \n\n \n \n  URL:https://fermi.univ-tlse3.fr/event/reviving-old-theories-with-2d-materials-ji-ung-lee-seminar-cemes-10-09-2024-11h/ LOCATION:Salle de conférence\, Bâtiment 3R4 CATEGORIES:CEMES,Events,Seminars END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20240910T140000 DTEND;TZID=Europe/Paris:20240910T153000 DTSTAMP:20260418T084202 CREATED:20240824T082047Z LAST-MODIFIED:20240829T082333Z UID:10944-1725976800-1725982200@fermi.univ-tlse3.fr SUMMARY:Information theory bounds on randomness-based phase transitions. - (Noa Feldman / LPT / Seminar). - 10/09/2024\, 14H DESCRIPTION:Noa Feldman(Université de Tel Aviv) \nSeminar LPT\, 10/09/2024\, 14H\, 3R1\, seminar room\, 3rd floor \nAbstract : \nWe introduce a new perspective on the connection between many-body physics and information theory. We study phase transitions in models with randomness\, such as localization in disordered systems\, or random quantum circuits with measurements. \nUtilizing information-based arguments regarding probability distribution differentiation\, rigorous results for bounds on critical exponents in such phase transitions are obtained with a minimal amount of work.\nWe first demonstrate our method by rederiving the well known Harris criterion\, bounding \noareal-space and dynamical critical exponents in the Anderson localization transition. \nWe then move to obtain new bounds on critical exponents in many-body Fock space localization transition and localization in Coulomb-interactive models. Somewhat surprisingly\, our bounds are not obeyed by previous studies of these systems\, indicating possible inadequacies in their results\, which we discuss. Finally\, we apply our method to measurement-induced phase transition in random quantum circuits\, obtaining bounds transcending recent mapping to percolation problems. \n  \n
URL:https://fermi.univ-tlse3.fr/event/information-theory-bounds-on-randomness-based-phase-transitions-noa-feldman-lpt-seminar-10-09-2024-14h/ LOCATION:salle de séminaire 3ème étage\, Bâtiment 3r1 Université Toulouse III\, Toulouse\, 31400\, France CATEGORIES:Events,LPT,Seminars END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20240917T140000 DTEND;TZID=Europe/Paris:20240917T153000 DTSTAMP:20260418T084202 CREATED:20240916T090923Z LAST-MODIFIED:20240916T135235Z UID:10915-1726581600-1726587000@fermi.univ-tlse3.fr SUMMARY:From moiré to moiré-of-moiré states and their topologies in helical twisted trilayer graphene. - (Yuncheng Mao / LPT / Seminar). - 17/09/2024\, 14H DESCRIPTION:Yuncheng Mao (CINaM\, Marseille) \nSeminar LPT\, 17/09/2024\, 14H\, 3R1\, seminar room\, 3rd floor \nAbstract \nThe experimental and theoretical success in twisted bilayer graphene (TBG) opened a new domain in modern condensed physics\, now called « twistronics ». Such 2D vdW heterostructures offer various platforms for the study of strongly correlated materials and hopefully topologically protected high-temperature superconductivity\, paving the way to topological quantum computation and information in the future. Equipped with overly rich symmetries\, different quantum topologies also emerge in such systems. A close cousin to TBG is the twisted trilayer graphene (TTG). With only an additional graphene layer\, TTG exhibits significantly different properties than TBG\, with even higher tunability as well as distinct symmetries and topologies. We are especially interested in the helical twisted trilayer graphene (hTTG) where the top and bottom layers are rotated in opposite directions with respect to the middle layer. In this case\, two moiré patterns between neighboring layers coexist and are in general incommensurate. Therefore\, the mismatch between the two moiré periodicities gives rise to a higher-level moiré pattern on top of the moiré patterns\, referred to as the « moiré-of-moiré » or « supermoiré » pattern. With proper approximations\, we can ignore the supermoiré variations and access the electronic state at moiré scale. Interesting topological phase transition associated with the variation of twist angle and the stacking is identified. To evaluate the supermoiré states\, a theoretical framework is devised to treat it in the context of perturbed periodicity. This framework is quite general and can be applied to other physical systems. The supermoiré states can be obtained for certain twisted angles close to rational ratios. A pseudo-magnetic field effect due to the supermoiré modulation is revealed\, which is otherwise invisible by the trivial average of moiré properties over the supermoiré length scale. \nReferences : \n[1] Y. Mao\, D. Guerci\, and C. Mora\, Supermoiré low-energy effective theory of twisted trilayer graphene\, Phys. Rev. B 107\, 125423 (2023). \n[2] D. Guerci\, Y. Mao\, and C. Mora\, Chern mosaic and ideal flat bands in equal-twist trilayer graphene\, Phys. Rev. Research 6\, L022025 (2024). \n[3] D. Guerci\, Y. Mao\, and C. Mora\, Nature of even and odd magic angles in helical twisted trilayer graphene\, Phys. Rev. B 109\, 205411 (2024). URL:https://fermi.univ-tlse3.fr/event/tba-yuncheng-mao-lpt-seminar-17-09-2024-14h/ LOCATION:salle de séminaire 3ème étage\, Bâtiment 3r1 Université Toulouse III\, Toulouse\, 31400\, France CATEGORIES:Events,LPT,Seminars END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20240919T140000 DTEND;TZID=Europe/Paris:20240919T160000 DTSTAMP:20260418T084202 CREATED:20240915T080715Z LAST-MODIFIED:20240916T135312Z UID:10974-1726754400-1726761600@fermi.univ-tlse3.fr SUMMARY:Brain-like Computation with Percolating Networks of Nanoparticles. - (Simon Brown / LPCNO / Seminar). - 19/09/2024 DESCRIPTION:Séminaire LPCNO \nSimon Brown\, University of Canterbury\, Christchurch\, NZ \nSSeminar room\, INSA\, Build. 27\, Room 2.20 (2nd floor left) \nAbstract \nSelf-assembled networks of nanoparticles have recently emerged as important candidate systems for brain-like (or neuromorphic) information processing.[1] The essence of the approach is to take advantage of the intrinsic dynamical properties of these networks to implement brain-inspired approaches to computation.[2] \nOur percolating networks of nanoparticles (PNNs\, Fig 1(a)) are self-assembled via simple deposition processes that are completely CMOS compatible\, making them attractive for integration.[3] The tunnel gaps between particles (Fig 1(b)) turn out to have neuron-like properties\, which means that PNNs can be viewed as networks of neurons.[4] Neuron-like electrical spikes are generated when \nWe have explored brain-like computation with PNNs in two regimes\, beginning with simulations[5\,6\,7] that allow us to understand the processes and refine parameters\, and then moving to experimental demonstrations[8]. At low voltages\, the devices are amenable to reservoir computation and we have successfully demonstrated time series prediction\, non-linear transformation and spoken digit recognition.[5\,8] In the high voltage regime\, the spiking behaviour of the ‘neurons’ has been exploited to perform Boolean logic and MNIST classification[6]\, and\, most recently\, optimization tasks including specifically integer factorisation[7] \n[1] J. B. Mallinson et al\, Science Advances 5\, eaaw8438 (2019).\n[2] S. Shirai et al\, Network Neuroscience 4\, 432 (2020).\n[3] A. Sattar et al\, Phys. Rev. Lett. 111\, 136808 (2013).\n[4] R. K. Daniels\, et al Neural Networks 154\, 122 (2022)\, Phys. Rev. Applied 20\, 034021 (2023).\n[5] J. B. Mallinson et al\, Nanoscale 15\, 9663 (2023).\n[6] S. J. Studholme et al\, Nano. Lett. 23\, 10594 (2023).\n[7] S. J. Studholme et al\, in press\, ACS Nano (2024).\n[8] J. B. Mallinson et al\, Advanced Materials (2024); adma.202402319 URL:https://fermi.univ-tlse3.fr/event/brain-like-computation-with-percolating-networks-of-nanoparticles-simon-brown-lpcno-seminar-19-09-2024/ LOCATION:Salle 220\, LPCNO\, INSA – LPCNO : 135 avenue de Rangueil\, toulouse\, 31077\, France CATEGORIES:Events,LPCNO,Seminars END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20240927T103000 DTEND;TZID=Europe/Paris:20240927T123000 DTSTAMP:20260418T084202 CREATED:20240925T072507Z LAST-MODIFIED:20240925T075738Z UID:11003-1727433000-1727440200@fermi.univ-tlse3.fr SUMMARY:Expériences in silico sur biomolécules. - (Marie Brut / Seminar/ SFP). - 27/09/2024\, 11H DESCRIPTION:Marie Brut (Laas\, Toulouse) \nMarraine de la promotion 2024 du master “Physique Fondamentale\, Ingénierie Quantique et Matière Condensée »\nLieu : Salle de conférence\, nouveau Bâtiment 3R4 \nRésumé :\nCe séminaire présentera un des nombreux chemins permettant d’avancer dans la compréhension des mécanismes qui gouvernent l’activité des biomolécules à l’échelle atomique. Il s’articulera autour de deux activités complémentaires : \n\ni) d’une part le développement de nouvelles méthodologies\, principalement pour l’étude de la relation structure-fonction de molécules biologiques ;\nii) d’autre part\, l’application de ces méthodes à des systèmes biologiques et bio-hybrides. Ces deux activités sont intrinsèquement liées car la spécificité de chaque système d’étude nous conduit à choisir et adapter les outils\, voire à en développer ex nihilo.\n\nPar ailleurs\, mettre en oeuvre des approches originales nous permet de poser un regard nouveau sur les systèmes étudiés\, de proposer des expériences in silico sur-mesure et de considérer les objets biologiques dans de nouveaux environnements\, au-delà de leur fonction première URL:https://fermi.univ-tlse3.fr/event/experiences-in-silico-sur-biomolecules-marie-brut-seminar-sfp-27-09-2024-11h/ LOCATION:Salle de conférence\, Bâtiment 3R4 CATEGORIES:Events,Seminars,SFP / SFC END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Paris:20240930T140000 DTEND;TZID=Europe/Paris:20240930T160000 DTSTAMP:20260418T084202 CREATED:20240924T081638Z LAST-MODIFIED:20240925T080112Z UID:10976-1727704800-1727712000@fermi.univ-tlse3.fr SUMMARY:Interfaces and nanoalloys: formation\, dynamics and relevance in catalysis. - (Christophe Copéret / LPCNO / Seminar). - 30/09/2024 DESCRIPTION:Séminaire LPCNO \nChristophe Copéret\, ETH Zurich\, CH \nAmphi GEI13\, INSA\, Build. 19\, Room 13 (ground floor left) \nAbstract \nMost large-scale industrial processes rely on heterogeneous catalysts. Among them\, supported nanoparticles represent one of the largest classes\, for which the desired catalytic performances (activity\, selectivity and stability) often relate to specific combination of metals\, additives (promoters/poisons) and supports. The complexity of these multicomponent materials often relates to the use of conventional preparation methods in water\, associated dissolution/precipitation processes. They thus raise numerous questions on the role of each components\, and in particular on the role of specific compositions\, interfaces and alloying in driving catalytic properties. \nIn this context\, our group has developed synthetic methodologies to control the generation of active sites thanks to the concept of surface organometallic chemistry (SOMC). SOMC is anchored on molecular principles with the goal to understand the surface chemistry at a molecular level. It typically relies on controlling the density of functional groups like surface OH groups in oxide materials\, grafting molecular precursor to generate isolated metal sites\, following in many instances by a thermal treatment that removes the remaining ligands. This approach has been very successful in generating so-called single-site catalysts; it has also recently been shown to grow\, in a controlled manner\, nanoparticles with tailored compositions\, small and nanoparticle size distribution\, interfaces\, and even alloying. Furthermore\, these SOMC catalysts are specifically aimable to detailed characterization and operando spectroscopy\, hence the possibility to derive structure-activity relationships.[1] \nThis lecture focuses on showing how SOMC combined with state-of-the-art Operando spectroscopies\, in particular based on X-Ray Absorption (XAS) and IR\, augmented with computational modelling enable to understand the structure and the dynamics of active sites. The lecture will illustrate in particular how interfaces and/or alloys in nanoparticles are created and how these specific sites/interfaces evolve under reaction conditions and contributes to the catalytic events. This lecture will focus on two specific catalytic processes\, namely propane dehydrogenation and CO2 hydrogenation\,[2] which are two key industrial processes relevant to current and emerging strategies. Overall\, this lecture highlights how interfaces\, alloying and dynamics are driving the catalytic performances and how one need to revisit (open) our views on active sites in heterogeneous catalysis \nReferences:\n1 C. Copéret Single-Sites and Nanoparticles at Tailored Interfaces Prepared via Surface Organometallic Chemistry from Thermolytic Molecular Precursors. Acc. Chem. Res. 2019\, 52\, 1697–1708.\n2 a) Deciphering Metal-Oxide and Metal-Metal Interplay via Surface Organometallic Chemistry: A Case Study with CO2 Hydrogenation to Methanol. S. R. Docherty\, C. Copéret J. Am. Chem. Soc. 2021\, 143\, 6767–6780. b) Heterogeneous Alkane Dehydrogenation Catalysts Investigated via a Surface Organometallic Chemistry Approach. S. R. Docherty\, L. Rochlitz\, P.-A. Payard\, C. Copéret Chem. Soc. Rev. 2021\, 50\, 5806 – 5822 URL:https://fermi.univ-tlse3.fr/event/interfaces-and-nanoalloys-formation-dynamics-and-relevance-in-catalysis-cristophe-coperet-lpcno-seminar-30-09-2024/ CATEGORIES:Events,LPCNO,Seminars END:VEVENT END:VCALENDAR