2D materials exhibit tunable interlayer interactions due to weak van der Waals bonding, which influences magnetic ordering in 2D magnets. The stacking sequence and internal chemistry impact ferromagnetic (FM) or antiferromagnetic (AFM) ordering, as seen in materials like CrBr3, CrI3, and Fe5GeTe2, where doping with Co raises the Curie temperature and alters magnetic phases. Chemical disorder also affects magnetic properties, with Mn/Sb substitution promoting FM ordering in Mn(Bi,Sb)2Te4. However, understanding how the atomic structure affects macroscopic magnetic properties remains limited due to the coexistence of metastable configurations. Precise control over stacking and chemical order is needed to harness 2D materials' magnetic and quantum properties. Transmission electron microscopy (TEM), especially aberration-corrected STEM, is today one of the most powerful techniques, enabling atomic-scale imaging and spectroscopy, for studying structural and chemical properties of 2D materials. This PhD project aims to study the relationship between atomic structure, chemistry, and magnetic properties in epitaxial 2D layers like (Fe,Co)5GeTe2, combining growth via molecular beam epitaxy (MBE) with STEM-based structural and chemical analysis.
The Synchrotron Group at the Institut de Biologie Structurale in Grenoble is currently developing an innovative method called TR-FOX (Time-Resolved Functional Oscillation Crystallography). This technique aims to elucidate, firstly, the global dynamics of biological macromolecules in action and, secondly, their fine catalytic mechanism. It relies on the use of an injector capable of depositing onto the crystal, during the course of the X-ray diffraction data collection, a nanoliter droplet containing the substrate and cofactor of the studied reaction. This triggers the enzymatic reaction within the crystal. The approach can be combined with UV-Visible absorption spectroscopy to characterize the reaction kinetics more precisely. The goal is to obtain a series of structures during the catalytic cycle in order to make a molecular movie depicting the functioning of the enzyme. This thesis has two objectives: (i) improve and validate the TR-FOX method and, (ii) study the catalytic mechanism of two enzymes involved in carbon fixation either by capture or conversion of CO2.
The proposed topic is a collaborative project to exploit suspended magnetic disks as novel microwave transducers of orbital angular momentum. Our goal is to develop ultra-high fidelity opto-mechanical modulators operating at GHz frequencies by integrating magnetic materials into optical components. This innovative concept arises from recent progress in the study of angular momentum conservation laws by magnon modes in axi-symmetric cavities, leading to new opportunities to develop a more frugal, agile, and sustainable communications technology. Our proposed design has the potential to achieve coherent interconversion between the microwave frequency range in which wireless networks or quantum computers operate and optical network frequencies, which is the optimal frequency range for long-distance communications. In this regard, our proposal not only proposes new applications of magnonics to the field of optics not previously envisioned, but also builds a bridge between the spintronics and the electronic and quantum communities.
In this proposal, the elastic deformations are generated by the magnetization dynamics through the magneto-elastic tensor and its contactless coupling to a microwave circuit. We have shown that coherent coupling between magnons and phonons can be achieved by precisely tuning the magnetic resonance degenerate with a selected elastic mode via the application of an external magnetic field. We expect to achieve ultra-high fidelity conversion by focusing our study on micron-sized single crystal magnetic garnet structures integrated with GaAs photonic waveguides or cavities. In addition, we propose the fabrication of suspended cavities as a means to minimize further energy leakage (elastic or optical) through the substrate.
The first challenge is to produce hybrid materials that integrate high quality garnet films with semiconductors. We propose a radically new approach based on micron-thick magnetic garnet films grown by liquid phase epitaxy (LPE) on a gadolinium-gallium-garnet (GGG) substrate. The originality is to bond the flipped film to a semiconductor wafer and then remove most of the the GGG substrate by mechanical polishing. The resulting multi-layer is then processed using standard lithography techniques, taking advantage of the relative robustness of garnet materials to chemical, thermal or milling processes.
The second challenge is to go beyond the excitation of uniform modes and target modes with orbital angular momentum as encoders of arbitrarily large quanta of nJ? for mode multiplexed communication channels or multi-level quantum state registers. The project will take advantage of recent advances in spin-orbit coupling between azimuthal spin waves as well as elastic scattering of magnons on anisotropic magneto-crystalline tensors. In this project, we also want to go beyond uniformly magnetized state and exploit the ability to continuously morph the equilibrium magnetic texture in the azimuthal direction as a means of engineering the selection rules and thus coherently access otherwise hidden mode symmetries.
Silicon and Germanium spin qubits have made outstanding progress in the past few years. In these devices, the elementary information is stored as a coherent superposition of the spin states of an electron or hole confined in a quantum dot embedded in a Si/SiO2 or SiGe heterostructure. These spins can be manipulated electrically and are entangled through exchange interactions, allowing for a variety of one- and two-qubit gates required for quantum computing and simulation. Grenoble is promoting original spin qubit platforms based on Si and Ge, and holds various records in spin lifetimes and spin-photon interactions. At CEA/IRIG, we support the progress of these quantum technologies with state-of-the-art modelling. We are, in particular, developing the TB_Sim code, able to describe very realistic qubit structures down to the atomic scale if needed.
Spin shuttling has emerged recently as a resource for spin manipulation and transport. A carrier and its spin can indeed be moved (shuttled) coherently between quantum dots, allowing for the transport of quantum information on long ranges and for the coupling between distant spins. The shuttling dynamics is however complex owing to the spin-orbit interactions that couple the motion of the carrier to its spin. This calls for a comprehensive understanding of these interactions and of their effects on the evolution and coherence of the spin. The aim of this PhD is to model shuttling between Si/Ge spin qubits using a combination of analytical and numerical (TB_Sim) techniques. The project will address spin manipulation, transport and entanglement in arrays of spin qubits, as well as the response to noise and disorder (decoherence). The PhD candidate will have the opportunity to interact with a lively community of experimentalists working on spin qubits at CEA and CNRS.
Topological superconductivity has become a subject of intense research due to its potential for breakthrough in the field of quantum information. Bulk systems are a promising possibility, with candidates found mainly among unconventional superconductors, which are also strongly correlated electron systems. Today, only a few candidate compounds for topological bulk superconductivity exists, and they are mostly uranium-based heavy fermion superconductors. UTe2 is one of the most prominent candidates. The topological properties of the superconductors depends crucially on the topology of the Fermi surface.
In this project we want to set up a novel technique (for our team) relying on a tunnel diode oscillator circuit. This techniques is very sensitive to quantum oscillations, and to be well both to high magnetic fields and to high-pressure studies. First experiments concentrate on the novel superconductor UTe2, where the Fermi surface is only partly known. In further studies the topological properties of the ferromagnetic superconductors UCoGe and URhGe will be revised.
The development of surfaces that limit microbial proliferation is a crucial public health issue. In the context of manned flights to remote destinations such as low Earth orbit, the Moon and possibly Mars, biological contamination represents a significant threat to crew health and the preservation of space equipment. The microflora carried by the crew in enclosed habitats constitutes an unavoidable risk, accentuated by prolonged periods of isolation and dependence on closed environment life support systems. In addition to the risks to astronauts' health, biocontamination is known to damage critical equipment on board spacecraft. Furthermore, micro-organisms exposed to the space environment can develop resistance and mutate, transforming benign microbes into pathogens. To mitigate these risks, effective measures, such as filtration systems and self-decontaminating surfaces that limit bacterial proliferation, need to be put in place. The MATISS experiment (2016-2025), in which the SyMMES and PRISM laboratories were involved, explored the use of hydrophobic coatings to reduce biocontamination on board the ISS, but further improvements are needed, in particular to find alternative solutions to perfluorinated agents and antibiotics, but also applicable to a wide range of materials. Such advances could have a wide range of applications beyond space, including food safety (packaging), implantable materials, drinking water treatment, public transport hygiene, etc. The aim of this collaborative thesis between SyMMES and CEA-Leti in Grenoble is to develop sustainable antimicrobial coatings free from harmful substances, by exploring different functionalization methods, such as the formation of self-assembled monolayers, electropolymerization on conductive materials, and in a highly original way by implementing a new cold atmospheric plasma deposition method, suitable for large surfaces, and above all applicable to a wide range of different materials.
Each cell type, defined by its function and state, is characterized by a specific size range. Indeed, cell size within a specific cell type displays a narrow distribution that can vary from as much as several orders of magnitude between smaller cells, such as red blood cells, and large muscle cells. Interestingly, this size characteristic is essentially maintained during the life cycle of an individual and highly conserved among mammals. Altogether, these features suggest that maintaining “the right size” for a given cell could play an important role in performing its function.
The actin cytoskeleton, that can form different stable while dynamic intracellular architectures, plays a major role in the structural plasticity of cells in response to changes in shape and size. Our recent work suggests that actin networks developed within a cell scale with the actual size and volume of the cell. However, how cells adapt the turnover and organization of their numerous structures assembled from a limiting pool of actin monomers remains to be understood.
In this project, we thus propose to study the organization and dynamics of actin networks in selected cell types displaying distinct sizes. In particular, our study will focus on characterizing the impact of such networks organization/dynamics on different cellular functions such as cell migration or adaptability to environmental cues. The feedback between cytoskeletal architecture dynamics, cell size and function will also be addressed by perturbing the organization and dynamics of the actin cytoskeleton in these cells.
The hired joint UGA – KIT PHD candidate should be able to cover the work of the workpackage 1 and 2. He/she will also participate to technical meetings and have a good understanding on how the tasks of the other technical workpackages are executed, mainly by the partners with internal effort. As a whole, the PHD candidate will develop and optimize compact Computing in Memory architectures, provide high level models for further integration in large scale designs, perform validation of all proofs of concepts of new architectural implementations. He/she will be involved also in the design of algorithmic implementations of Bayesian Neural Networks adapted to the architecture. More in details, he/she will work on the following directions:
Design and optimization of the probabilistic neural networks, will be executed mostly in SPINTEC Laboratory in Grenoble, that will include:
1. full design stack of hardware accelerator without selector transistor for frequent Read and Write operations.
2. Design and validate an innovative architectural approach able to compensate for sneaky paths phenomena.
3. High-level modeling of the full crossbar architecture that includes the stochastic component.
4. Propose a full simulation and validation flow scalable to scaled to realistic architecture size and parameters that implement Bayesian tasks.
5. Perform Delay, power consumption and area overhead figures of merit
We want to focus on epigenetic dysregulation in Huntington’s Disease (HD), a pathogenic mechanism implicated in accelerated aging of striatal neurons. Specifically, we will investigate the interplay between altered energy metabolism and epigenetic impairment in HD striatal neurons to identify new targets/pathways for disease-modifying intervention. We aim to obtain detailed maps of histone post-translational modifications (PTMs), especially of methylations, acetylation and the recently described lactylation, which might be critical in the HD brain. Indeed, these PTMs are tightly regulated by the metabolic status of the cells. We will use proteomics which is the best suited approach to identify and quantify multiple protein PTMs. We consider working on the striatum of WT, R6/1 transgenic mice and the more progressive Q140 knock in model at various stages of disease, to assess evolution of histone PTMs and metabolism with aging. Additionally, to get a dynamic view of the links between metabolic and epigenetic imbalance in HD, we will inject intraperitoneally HD mice and controls with 13C-glucose and analyze over a time course the incorporation of 13C into histone PTMs. Finally, acetyl-CoA, the precursor for histone lysine acetylation, has been shown to be locally produced in the nucleus, by either acetyl-CoA synthetase 2 (ACSS2), ATP-citrate lyase (ACLY) or the pyruvate dehydrogenase complex. Regarding lactylation, it is currently unknown where, and by which enzymes, the pool of lactate used for modifying histone lysines by lactylation is produced. ACSS2 is a very good candidate, as it can catalyze the production of acyl-CoA molecules from the corresponding short chain fatty acids (SCFA). To address the question of the production of metabolites in the vicinity of chromatin in striatal cells, we will use epigenomics (ChIPseq or CUT&tag) to get the genomic distribution of ACSS2 and ACLY and compare it to distributions of acetyl and lactyl histone marks.