Description du sujet de thèse

The elementary microscopic deformation processes at play in such materials have been understood long ago in amorphous metals, and more recently in concentrated suspensions : they have been identified and described as shear transition zones (STZ), corresponding to localized regions in which local rearrangement of the particles packing changes. Numerical simulations have shown that, if the system is ''trained'', by the application of a periodic oscillation of amplitude $\gamma$, in the plastic regime, then, subsequent deformation of amplitude different from $\gamma$ leads to irreversible trajectories, while microscopic trajectories under a deformation of amplitude equal to the training amplitude $\gamma$ are reversible. This means that the microscopic plastic rearrangements may be reversible. \\
We will perform an experimental study of the reversible of particles trajectories in the plastic regime, after periodic ''training''. Thus, we will study the characteristic of particles trajectories as a function of the previously applied deformation~\cite{dmytropre}. To this goal, we have developed a light scattering under shear setup that allows to probe the trajectories of the particles over length scales ranging from their radius to several particles diameters~\cite{dmytrorsi}. We will quantify the reversibility of the particles trajectories as a function of the orientation of the scattering vector relative to the flow and as a function of its magnitude.
This will help to elucidate the fundamental mechanisms at play in the elastoplastic transition in an amorphous system, both close to the glass transition and deep in the glass state.
[1] D. Fiocco, G. Foffi and S.Sastry Encoding of Memory in Sheared Amorphous Solids, Physical Review Letters, 112, 025702, 2014. [2] D. Kushnir, N. Beyer, E. Bartsch and P. H ́ebraud Wide-angle static and dynamic light scattering under shear, Review of Scientific Instruments, 92, 025113, 2021.

Contexte de travail

The PhD will be affiliated with the Doctoral School of Physics and Physical Chemistry at the University of Strasbourg (ED182).

The candidate (M/F) will be hosted at the Institute of Physics and Chemistry of Materials of Strasbourg (Department of Optics and Nanophotonics, Biophysics and Soft Matter Team).
IPCMS, a joint research unit under the supervision of CNRS and the University of Strasbourg (UMR704), is an internationally recognized research and training center in the field of materials and nanosciences. Staff members are affiliated with CNRS (INP, INC) as well as with the University of Strasbourg (Faculties of Physics & Engineering, Chemistry, ECPM, and Télécom Physique Strasbourg).
The laboratory is organized into 3 physics departments and 2 chemistry departments with strong interdisciplinary interactions. Research at IPCMS is based on solid expertise in experimental science, theory, and modeling.
IPCMS possesses a large and advanced set of instruments for the fabrication and study of materials or devices at all spatial (from atom to bulk) and temporal (from femtosecond to attosecond) scales, along with recognized skills in atomic-scale theory and modeling, combining various approaches (quantum mechanics, DFT, molecular mechanics, finite elements, etc.).

The candidate (M/F) must hold a Master's degree. They must demonstrate solid knowledge of general physics and a strong interest in experimental physics.

Applications must include a detailed CV, a cover letter, a summary of the Master's thesis, and transcripts from both the first and second years of the Master's program.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.