La science-fiction explore le champ des possibles grâce à des expériences de pensée. Par jeu, demandons-nous avec elle ce que serait devenu l'humanité sur une Terre différente, plus massive par exemple, ou avec des anneaux. Aurions-nous découvert aussi rapidement les lois de la mécanique céleste si la Terre était en orbite autour d'une d'étoile binaire ? Quel impact aurait eu un ciel différent de celui que nous observons quotidiennement ? Finalement, peut-on imaginer quelle serait notre représentation du monde si la Terre était différente ? C'est certainement dans cette capacité à interroger le réel par la pensée, en se posant la languissante question « Et si… ? », que se trouve le lien secret qui unit science et science-fiction.

Roland Lehoucq est astrophysicien au CEA de Saclay. Il est aussi enseignant (Université Paris Cité, ENS Paris-Saclay et Science Po Rennes) et auteur de nombreux ouvrages faisant dialoguer sciences et science-fiction. Depuis 2012, il est président des Utopiales, le festival international de science-fiction de Nantes.

I will present results from our lab on two classes of bottom-up grown nanostructures with applications within quantum technology. First, I will present developments in selective area growth of III-V materials both in terms of scalability and fundamental physics. We have shown how incorporating multiplexing circuits directly on the sample enabled the measurement of hundreds of nominally identical devices during the same measurement run, bringing statistical significance to parameters such as mobility and threshold voltage. We further demonstrate the scalability potential by defining quantum dots in 20 different devices using only three shared crossbar gates. Part of the interest in III-V based nanostructures is due to the interesting physics that arises when they are coupled to superconductors. I will present our results on using quantum interference phenomena to study the symmetries present in III-V/superconductor hybrids.

Finally, I will present results on complex oxide micro-membranes. The interface between materials such as SrTiO3 and LaAlO3 hosts a 2DEG which exhibits signatures of strongly correlated physics, including electron pairing, spin ordering, and superconductivity. However, studying nanodevices in these materials via electron transport is hindered by the failure of traditional fabrication methods. We have recently had success using bottom-up grown SrTiO3/LaAlO3 micro-membranes as the basis for our nanodevices, and I will present preliminary results from these.

Relevant references :
    Dāgs Olšteins et al, Nature Communications, 14, 7738 (2023)
    Dags Olsteins et al, Nano Letters 24, 6553 (2024)
    Ricci Erlandsen et al, Nano Letters 22, 4758 (2022)

Abstract

Les trajectoires actuelles de développement ont entraîné des modifications graves, pour certaines irréversibles, du climat et de la biodiversité. Dans cette présentation, nous discuterons des causes et des responsabilités différentiées dans ces changements globaux. nous aborderons également les options évaluées par le GIEC pour parvenir à limiter le réchauffement climatique et les compromis ou synergies de ces options avec les autres enjeux de développement durable.

About the author
Sophie Szopa est directrice de recherche CEA au Laboratoire des Sciences du Climat et de l’Environnement. Spécialiste en chimie de l'atmosphère, elle utilise des modèles numériques pour étudier comment la chimie intervient dans la modification de composition de l’atmosphère et comment cela affecteclimat et qualité de l'air. Elle a coordonné un chapitre sur les composés chimiques à courte durée de vie agissant sur le climat du rapport du GIEC qui évalue les connaissances des bases physiques du changement climatique (AR6-WGI, publié en 2021) et contribué au rapport de synthèse des rapports du 6ème exercice d'évaluation du GIEC paru en mars 2023. Dans le cadre du 7ème cycle d'évaluation du GIEC, elle est également coordonnatrice et auteure du prochain rapport spécial sur le changement climatique et les villes à paraître en 2027. De 2022 à 2024, elle a été vice-présidente en charge du Développement Soutenable de l'Université Paris-Saclay.

Crédit Photo @IPCC

The integration of additive manufacturing principles with thin film deposition technologies presents significant opportunities for advancing material processing capabilities. While conventional lithography and vapor-phase methods have demonstrated reliable performance, they face fundamental limitations in process flexibility and step reduction. This work explores a novel approach to spatial atomic layer deposition that addresses these constraints. The miniaturization of Spatial Atomic Layer Deposition (SALD) technology introduces specific challenges in gas flow control and precursor delivery. ATLANT 3D presents a micro-nozzle system enabling Direct Atomic Layer Processing (DALP), which achieves localized deposition through precise gas flow confinement within micrometer-scale regions. The system maintains conventional ALD surface chemistry while enabling selective area processing. Initial characterization demonstrates that this approach achieves crystalline thin film formation with quality comparable to conventional ALD methods. The localized nature of the process enables rapid prototyping of materials and processes as well as novel device architectures by reducing the number of required lithography steps. The system demonstrates compatibility with standard ALD precursor chemistries while providing enhanced spatial selectivity.

Experimental validation of this technique has been conducted across several application domains. Temperature sensor fabrication demonstrates sensitivity comparable to conventional methods, while optical applications such as Bragg mirrors exhibit expected reflectivity profiles. The ability to create overlapping depositions enables complex multilayer structures, as evidenced by the formation of ultrathin optical elements. Additional applications in catalysis and microelectronics highlight the versatility of the approach. This work demonstrates the feasibility of miniaturized spatial ALD for selective area processing. The results suggest potential applications in rapid prototyping and novel device architectures, particularly where traditional lithography poses limitations.

The elastic coupling between a magnetic film and the substrate is desired in SAW-FMR devices and in magnetoacoustics [1–3] when one harnesses the interaction between a surface acoustic wave (SAW) hosted by a piezoelectric substrate and the magnetization dynamics of a magnetic film on top. We first designed an experiment specifically meant to quantify the magneto-elastic and magneto-rotation field that arise from the mechanical deformations induced by a SAW. For this we prepared magnetic discs possessing a vortex ground state. The discs can be excited either by a remotely generated SAW or by an inductive antenna placed on top of the disc. The vortex dynamics can be measured by magnetic resonance force microscope (MRFM). The antenna has broadband frequency capability and can induce the gyrotropic dynamics of the vortex. The SAWs can also induce this dynamic, provided that the vortex gyration frequency is resonant with that of the SAW [4]. This ability to excite the same dynamics with a classical antenna or with magneto-acoustic interaction allows to quantify the effective magneto-elastic and magneto-rotation fields. It appears that the symmetry of the magneto-acoustic interactions deserved to be revisited. We did such analysis using micromagnetic simulation and analytical calculations. In addition, the symmetry of the coupling can be conveniently studied when studying the coupling of spin waves (SWs) in synthetic antiferromagnets (SAFs) to SAWs [5]. For this we calculated the layer-resolved susceptibility tensor of a SAF, the effective magneto-elastic and magneto-rotation fields associated to a travelling elastic wave, and the power irreversibly transferred by the elastic wave to the magnetic layers. In particular, we showed that in SAF the complementary angular dependencies of the acoustic and optical SW modes makes it possible to excite spin waves for any relative orientation of magnetization and acoustic wavevector.

[1] M. Weiler et al. Phys. Rev. Lett. 106, 117601 (2011).
[2] P. Kuszewski et al.  Phys. Rev. Appl. 10, 034036 (2018).
[3] P. Rovillain et al.  Phys. Rev. Appl. 18, 064043 (2022).
[4] R. L. Seeger et al. under review, arXiv:2409.05998.
[5] R. L. Seeger et al.  Phys. Rev. B. 109, 104416 (2024)

- List of authors and affiliations : 
R. L. Seeger(a,b), F. Millo(a), L. La Spina(c), V. Laude(c), A. Bartasyte(c), S. Margueron(c), G. Soares(b) , L. Thevenard(a), C. Gourdon(a), J.-V. Kim(a), C. Chappert(a), A. Solignac(b), G. de Loubens(b), T. Devolder(a)
(a) Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Saclay 91120 Palaiseau, France
(b) SPEC, CEA, CNRS, Univ. Paris-Saclay, 91191 Gif-sur-Yvette, France
(c) Univ, de Franche-Comté, CNRS, Institut FEMTO-ST, 26 rue de l’Epitaphe, 25000 Besançon, France
(d) Institut des Nanosciences de Paris, Sorbonne Université,CNRS, UMR 7588, 4 place Jussieu, F-75005 Paris, France

- Bio : Rafael Lopes Seeger holds a Bachelor's and a Master's degree in Physics (2018) from the Federal University of Santa Maria (UFSM), Brazil, and a Ph.D. in Physics (2021) from the Université Grenoble-Alpes at the SPINTEC laboratory in Grenoble, France. Since 2022 he is a postdoctoral researcher working at SPEC (CEA-Saclay ) and C2N (CNRS, Université Paris Saclay) on projects involving magnon-phonon coupling and nonlinear effects in spin waves.