The aim of the thesis is to perform attosecond photoemission spectroscopy on molecules in the gas and liquid phase exploiting a novel high repetition rate Ytterbium laser system. These studies will unveil the processes of photoionization of inner/outer shells and the dynamics of electron scattering in real time.
Spin electronics, thanks to the additional degree of freedom provided by electron spin, enables the deployment of a rich physics of magnetism on a small scale, but also provides breakthrough technological solutions in the field of microelectronics (storage, memory, logic, etc.) as well as for magnetic field measurement.
In the field of life sciences and health, giant magnetoresistance (GMR) devices have demonstrated the possibility of measuring the very weak fields produced by excitable cells on a local scale (Caruso et al, Neuron 2017, Klein et al, Journal of Neurophysiology 2025).
Measuring the information contained in the magnetic component associated with neural currents (or magnetophysiology) can, in principle, provide a description of the dynamic, directional and differentiating neural landscape. It could pave the way for new types of implants, thanks to their immunity to gliosis and their longevity.
The current bottleneck is the very small amplitude of the signal produced (<1nT), which requires averaging the signal in order to detect it.
Tunnel magnetoresistances (TMR), in which a spin-polarised tunnel current is measured, offer sensitivity performance that is more than an order of magnitude higher than GMR. However, they currently have too high a level of low-frequency noise to be fully beneficial, particularly in the context of measuring biological signals.
The aim of this thesis is to push back the current limits of TMRs by reducing low-frequency noise, positioning them as break sensors for measuring very weak signals and exploiting their potential as amplifiers for small signals.
To achieve this objective, an initial approach based on exploring the materials composing the tunnel junction, in particular those of the so-called free magnetic layer, or on improving the crystallinity of the tunnel barrier, will be deployed. A second approach, consisting of studying the intrinsic properties of low-frequency noise, particularly in previously unexplored limits, at very low temperatures where intrinsic mechanisms are reached, will guide the most promising solutions.
Finally, the most advanced structures and approaches at the state of the art thus obtained will be integrated into devices that will provide the building blocks for going beyond the state of the art and offering new possibilities for spin electronics applications. These elements will also be integrated into systems for 2D (or even 3D) mapping of the activity of a global biological system (neural network) and for evaluating capabilities for clinical cases (such as epilepsy or motor rehabilitation).
It should be noted that these improved TMRs may have other applications in the fields of physical instrumentation, non-destructive testing, and magnetic imaging.
To reduce the environmental and/or the energetic impact of vehicles, a favored method is to decrease the mass of prime materials used to build them, that being done without hindering their mechanical performances. In this field, the use of mechanical metamaterials has been a major breakthrough. These metamaterials, generally created using additive manufacturing techniques, have a microscopic truss structure. They are porous by design, and thus very lightweight, and the distribution of their microscopic beams or tubes (i.e. their architecture) can be chosen to make them as stiff as possible, making them choice candidates for high technology applications where the rigidity-density ratio is paramount, such as aerospatial research (https://en.wikipedia.org/wiki/Metallic_microlattice).
For the most part however, metamaterials that have been designed up to now present periodical architectures. As a consequence, their mechanical behavior is inherently anisotropic, which makes them difficult to model using material mechanics conventional approaches, and strongly limits their usage in various possible fields of applications. In recent works, we have developped a new class of microlattice metamaterials with a random spatial distribution of beams, generated with a combination of random close packing and Delaunay triangulation algorithm then 3D-manufactured. These metamaterials show an isotropic mechanical behavior, and their stiffness-density ratio reaches the theoretical limit for porous materials. They are neverheless still fragile and subject to fracture and yielding.
The aim of this PhD project is to toughen these metamaterials based on techniques and mechanisms from polymer and soft matter physics. Our hypothesis is that including in a controlled statistical way structure heterogeneities, at the node level by modulating the connectivity or at the beam level by changing their section or shape, can allow toughening of the metamaterial. Indeed, localized heterogeneities can introduce mechanical dissipations in the network at various scales. The work of this project will consist in experiementally characterizing the mechanical properties of the metamaterials and to compare them to their homogeneous equivalent, and to describe their fracture resistance. Mechanical tests will be performed on an experimental setup conceived in the SPHYNX group. Analysis of the local and global deformation will be performed using different experiemental methods, in order to detect micro crack events with precision. An additionnal theoretical approach completed by numerical simulations based on fuse network and random beam models can also be discussed.
A strong interest for instrumentation and teamwork is requested for this project with a major experimental component. Proficiencies in experimental mechanics, material sciences and/or statistical physics are desirable. Some knowledge in modelization and numerical simulations are a bonus without being required. This project has both fundamental and applied interests and can help the student find prospects both in academia and in industrial opportunities.
The main objective of this thesis is to model the mechanisms of rare earth ion emission from ionic liquids subjected to an intense electric field, in order to identify the conditions favorable to the emission of weakly complexed ions.
The aim is to establish rational criteria for the design of new ILIS sources suitable for the localized implantation of rare earths in photonic devices.
The thesis work will be based on large-scale molecular dynamics simulations, reproducing the emission region of a Taylor cone under an electric field.
The simulations will be compared with emission experiments conducted in parallel by the SIMUL group in collaboration with Orsay Physics TESCAN, using a prototype ILIS source doped with rare earths. Comparisons of measurements (mass spectrometry, energy distribution) will enable the models to be adjusted and the proposed mechanisms to be validated.
Since the 1950s, the use of petroleum-based plastics has encouraged the emergence of a consumption model focused on the use of disposable products. Global plastic production has almost doubled over the last 20 years, currently reaching 468 million tons per year. These non-biodegradable plastic are the source of numerous forms of environmental pollution. Since the 1950s, only 9% of the wastes have been recycled. The majority have been incinerated or sent to landfill. In the current context of this linear economy, health, climate and societal issues make it essential to transition to a circular approach to materials. This evolution requires the development of recycling methods that are both effective and robust. While the most common recycling methods currently in use are mainly mechanical processes that apply to specific types of waste, such as PET plastic bottles, the development of chemical recycling methods appears promising for treating waste for which no recycling channels exist. These innovative chemical processes make it possible to recover the carbonaceous material from plastics to produce new ones.
Within this objective of material circularity, this doctoral project aims to develop new chemical recycling routes for mixed oxygen/nitrogen plastic waste such as polyurethanes (insulation foam, mattresses, etc.) and polyamides (textile fibres, circuit breaker boxes, etc.), for which recycling routes are virtually non-existent. This project is based on a strategy of depolymerizing these plastics by the selective cleavage of the carbon-oxygen and/or carbon-nitrogen bonds to form the corresponding monomers or their derivatives. To do that, catalytic systems involving metal catalysts coupled with abundant and inexpensive reducing agents will be developed. In order to optimize these catalytic systems, we will seek to understand how they proceed and the mechanisms involved.
Understanding the electronic properties of valence electrons in nano-objects is not only of fundamental interest but also essential for the design of next-generation optoelectronic devices. In such systems, electron confinement in low-dimensional structures gives rise to unique properties.
These properties are inherently linked to fundamental characteristics of matter and the associated quantum fluctuations. More recently, concepts such as quantum entanglement and Fisher quantum information have been connected to spectroscopic properties. On the other hand, these spectroscopic properties can be probed through experimental techniques, including absorption, photoemission, and inelastic X-ray scattering.
Recently, we demonstrated that the widely used formalism to study isolated nano-objects was not adapted, and that it affected the calculated optical properties. We evidenced, theoretically and experimentally, that for the two-dimensional objects, the optical response contained, beyond the transverse contribution, a resonance coming from the plasmon, which corresponds to a longitudinal response. The role of the interfaces revealed to be determinant. The project of this year is to have a critical analysis of the optical properties of unidimensional objects.
Beyond the fundamental characterization of the 1D dielectric function, this research will explore its connection to quantum entanglement and Fisher quantum information—concepts that, to date, have not been investigated in low-dimensional systems.
The development of cost-effective, high-energy-density solid-state batteries (SSBs) is essential for the large-scale adoption of next-generation energy storage technologies. Among various cathode candidates, LiFePO4 (LFP) and LiFe1??Mn?PO4 (LFMP) offer safety and cost advantages but suffer from low working voltages and limited kinetics compared to Ni-rich layered oxides such as LiNi0.85Mn0.05Co0.1O2 (NMC85). To balance energy density, rate capability, and stability, this PhD project aims to develop blended cathodes combining LFMP and NMC85 in optimized ratios for solid-state configurations employing sulfide electrolytes (Li6PS5Cl). We will investigate how fabrication methods- including slurry-based electrode processing and binder-solvent optimization- affect the electrochemical and structural performance. In-depth operando and in situ characterizations (XRD, Raman, and NMR) will be conducted to elucidate lithium diffusion, phase transition mechanisms, and redox behavior within the blended systems. Electrochemical impedance spectroscopy (EIS) and titration methods will quantify lithium kinetics across various states of charge. By correlating processing conditions, microstructure, and electrochemical behavior, this research seeks to identify optimal cathode compositions and manufacturing strategies for scalable, high-performance SSBs. Ultimately, the project aims to deliver a comprehensive understanding of structure–property relationships in blended cathodes, paving the way for practical solid-state battery technologies with enhanced safety, stability, and cost efficiency.
During photoelectrolysis (or solar water splitting), charge transfer at the photoanode / electrolyte interface is determined by the alignment between energy bands, both at the electrode and electrolyte side. Surface potential of the electrode plays a major role on the final band bending and thus charge separation at the interface. Also called electrochemical surface potential, it varies as a function of material environment (vacuum, air, water, etc.). The objective of this thesis is to address the OER (Oxygen Evolution Reaction) at the photoanode / electrolyte interface in terms of energy bands and in particular from the electrochemical surface potential perspective. Thus, during this thesis the student will characterize surface potentials of a series of catalytically activated metal oxide photoanodes in contact with different environments (vacuum, variable humidity air, water) and correlate it to photoelectrochemical activity. PhD student’s activity will be structured around fours axes: i) synthesis of photoanodes; ii) photoelectrochemical activity characterization; iii) characterization by atomic force microscopy (AFM) correlated with Kelvin force microscopy (KPFM); iv) synchrotron X-ray spectromicroscopies (STXM, XPEEM) and near ambient pressure photoemission (NAP-XPS). The student will be hosted at the SPEC laboratory at CEA-Saclay for the duration of the thesis. HisHer work is part of a long-standing collaboration between SPEC and SOLEIL.
Recent advances in ultrafast optics and the control of highly nonlinear light–matter interactions now make it possible to generate attosecond light pulses (1 as = 10?¹8 s) through High-Order Harmonic Generation (HHG). This process converts a femtosecond laser pulse into coherent, ultrashort radiation in the extreme ultraviolet (XUV) range (10–150 eV). These unique light sources enable access to electronic dynamics on sub-femtosecond timescales and allow the probing of element-specific transitions that were previously only achievable at large-scale facilities such as synchrotrons. The Attophysics Group at LIDYL, a pioneer in the generation, characterization, and application of attosecond pulses, has recently developed sources driven by beams carrying spin (SAM) or orbital (OAM) angular momentum, opening new avenues for studying chiral and magnetic dynamics. Building on these advances, this PhD project aims to synthesize light fields with time- and space-dependent chirality, exploiting in particular the often-neglected longitudinal component of the electric field. Three regimes will be explored: a linear regime (XUV/IR pump–probe), a strongly nonlinear regime (structured visible–IR fields in chiral samples), and a weakly nonlinear regime (IR pump/XUV probe). This work will open a new class of attosecond physics experiments, bridging fundamental exploration and emerging applications.
The student will acquire practical knowledge about lasers, in particular femtosecond lasers, and hands on spectrometric techniques of charged particles. They will also study strong field physical processes which form the basis for high harmonic generation. They will become an expert in attosecond physics. The acquisition of analysis skills, computer controlled experiments skills will be encouraged although not required.
Details at https://iramis.cea.fr/lidyl/pisp/150720-2/
An emerging pathway for quantum information is the use of flying electronic charges, such as single-electron excitations, as qubits.
These flying qubits present a key advantage: their intrinsic Coulomb interaction, which enables deterministic two-qubit gates and applications in quantum sensing.
Compared to photonic qubits, they therefore provide a natural means to overcome certain fundamental limitations.
Their main drawback lies in rapid decoherence, but this challenge can be mitigated by operating at ultrafast timescales, on the order of a picosecond.
An additional strategy involves exploiting the topological protection provided by Majorana modes, non-Abelian quasiparticles that are insensitive to local perturbations.
So far, most research has focused on localized 0D modes (at the ends of superconducting nanowires), with no conclusive experimental demonstrations.
This project proposes a new approach based on 1D chiral Majorana modes, offering a pathway toward topologically protected flying qubits.
The ambition is to establish a novel platform for quantum computing and quantum sensing.
This platform will exploit engineered multilayer graphene, combining the quantum anomalous Hall effect, superconductivity, and chiral Majorana modes.