Thesis, internship, and post-doc opportunities
169 results found
[Thèse]
Structure of the Solid Electrolyte Interface on electrodes for lithium batteries
Offer N°: 2328
Lithium batteries are currently developped for many applications and especially for the electric vehicles. It appears necessary to improve their power, density of energy and lifetime. They are formed of two insertion electrodes of lithium ions and an electrolyte. It is well known that upon cycling a passivation layer is developped on electrode called solid electrolyte interface (or SEI).
Lithium batteries are currently developped for many applications and especially for the electric vehicles. It appears necessary to improve their power, density of energy and lifetime. They are formed of two insertion electrodes of lithium ions and an electrolyte. It is well known that upon cycling a passivation layer is developped on electrode called solid electrolyte interface (or SEI). These layers are necessary to avoid the electrolyte degradation but they should be highly permeable to lithium ions. The objective of the PhD thesis will be the characterization of these layers (composition, thickness, porosity, ...) using techniques such as the scanning electrochemical microscopy, the Atomic Force Microscopy (AFM) combined with nanomechanical and infrared measurements. X-ray and/or neutron relectivity will be tentatively used for additional characterization. This basic research study will be performed in collaboration with a technical research team on more or less aged electrodes and model support and in situ analysis protocols will be developped.
[Thèse]
Mesoscopic current fluctuations in Multiple Andreev Reflexion regime
Offer N°: 2321
The possibility to reverse the sign of the current-current cross-correlation in multiterminal nanostructures has attracted both theoretical and experimental interest in the last decade. Indeed, while the cross-correlation is always negative in non-interacting fermionic devices, a positive cross-correlation is the signature of strong interactions in many-body systems.
The possibility to reverse the sign of the current-current cross-correlation in multiterminal nanostructures has attracted both theoretical and experimental interest in the last decade. Indeed, while the cross-correlation is always negative in non-interacting fermionic devices, a positive cross-correlation is the signature of strong interactions in many-body systems. Moreover, a strong effort in quantum nanoelectronics is now directed towards the generation of Einstein-Podolsky-Rosen pairs of electrons, and the cross-correlation would be a useful tool to detect their entanglement.
The goal of the PhD work will be to characterize in details the elementary processes of charge transfer in quantum mechanically coherent hybrid devices with several superconducting terminals, when electrons are transferred by Multiple Andreev Reflexions. The focus will be on the interplay between the AC Josephson and dissipative quasiparticle currents, on the spin resolved correlation and their relation with spin entanglement, as well as on the large sample-to-sample fluctuations of the current that could possibly arise in these structures.
[Thèse]
Electronic transport and dynamics of the magnetization in hybrid superconducting/ferromagnetic structures
Offer N°: 2322
The proximity effect in a ferromagnetic metal in contact with a superconductor is characterized by a spatial oscillation of the induced pair correlation function. This originates into oscillations of the critical current in S/F/S Josephson junctions when the width of the F layer varies. Noncolinear magnetic domains can also generate a long range proximity effect. These results assume a static configuration of the magnetization.
The proximity effect in a ferromagnetic metal in contact with a superconductor is characterized by a spatial oscillation of the induced pair correlation function. This originates into oscillations of the critical current in S/F/S Josephson junctions when the width of the F layer varies. Noncolinear magnetic domains can also generate a long range proximity effect. These results assume a static configuration of the magnetization. The goal of the PhD will be to study theoretically the new properties that emerge when the magnetization varies in time.
The student will consider the effect of the magnetization dynamics on the electronic transport in S/F and S/F/S junctions. Specifically, he/she will consider the case when the precession frequency of the magnetization resonates with the Josephson frequency or the frequency of an external ac bias. He/she will then consider the coupling between the dynamics of the superconducting phase and the magnetization. The study will allow a better understanding of the basic mechanisms for spin transfer and relaxation in these structures, with possible applications in the field of spintronics.
[Thèse]
Contribution to the study of phenomena involved in the direct bonding at low temperature layers of metal and metal oxide.
Offer N°: 2303
Direct bonding is a physical phenomenon that allows two surfaces to adhere spontaneously without added material. This phenomenon has been studied extensively in research and companies such as SOITEC TRACIT or commercialize products based on this technology. Research still active have to implement physical and chemical models for better understanding of this phenomenon of adhesion.
Direct bonding is a physical phenomenon that allows two surfaces to adhere spontaneously without added material. This phenomenon has been studied extensively in research and companies such as SOITEC TRACIT or commercialize products based on this technology. Research still active have to implement physical and chemical models for better understanding of this phenomenon of adhesion. However, these models do not currently process that surfaces where silicon oxide and silicon can take into account that the chemistry of surfaces.
Currently, for innovative applications of photovoltaic, or three-dimensional integration of power electronics, it is imperative to have a technical report or film circuit using a direct bonding electrically conductive ( connections with local or not) and heat dissipation. The bonding metal layer is then an excellent candidate.
We hope in the thesis proposed, leading to a physicochemical model of such direct bonding using new layers of metal bonding and metal oxide.
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