Functional Thin Film Mechanics
The activities of the OR concern the mechanical properties of thin films. It takes advantage of recent developments in the elaboration of functional thin films by PVD, using the two magnetron chambers that have been recently set up.
Studies on alloys and complex compounds (intermetallics, metallic glasses, high entropy alloys (HEAs)) in the form of thin films on various substrates (silicon, metallic, glass, polymers) are carried out according to the targeted applications (protective coating, optics, flexible electronics, …).
The OR takes advantage of this new axis to increase its interactions with the researchers of the OR plasma/surface interaction. The aim is to better characterize the plasma present in the chamber, and to better control the deposition conditions and the thin film microstructures obtained.
In terms of characterization, we are working in two directions: The first one is to study the links between structure, surface acoustic wave measurements and mechanical properties of thin films. The recently acquired equipments (picosecond acoustic, in situ temperature chamber) are coming to maturity allowing a unique thermo-elastic characterization in the field of metallurgical thin films. The objective is to find the links between elaboration processes, microstructure/elastic constants and their evolution at high temperature, our in-situ techniques allowing measurements up to 1600°C. These measurements are advantageously completed by DFT calculations of structure, elastic constants and thermal stability. These means are implemented within the framework of industrial collaborations with Saint-Gobain Recherche and Essilor, national academic collaborations with G. Abadias (Pprime), as well as international collaborations with D. Depla (Gent University), D. Duday (CRP Gabriel Lipmann, Luxembourg) and Q.M. Hu (China, Institute of Metal Research).
The second direction concerns the development of thin films and nanostructures on flexible substrates. We take advantage of all the characterization techniques developed during the last years (tensile tests coupled with AFM/optics and in situ resistivity measurements), allowing us to study the multifissure/buckling phenomena in model systems (metals) or more complex systems (intermetallics, HEAs), in collaboration with the MECAMETA axis as well as with Simap (Grenoble) for the modelling of the phenomena (variational and finite element approaches). We also continue to invest in the DiffAbs line of the Soleil synchrotron to use the biaxial traction machine for these flexible systems, with a greater effort towards large deformations. Moreover, in collaboration with the OR “magnetism of nanostructures”, we continue to study the magnetomechanical behavior of thin films and nanostructures on flexible substrates. In addition to the recently developed techniques, we are currently designing a MOKE magnetometer adapted to the above mentioned biaxial machine, in the framework of a DIM Nano-K project that we are carrying out with the DiffAbs line. The studied systems are magnetic thin films studied in common with the first direction (intermetallics, HEAs (magnetic)). In addition, we are developing flexible magnonic systems, in collaboration with the group of A.O. Adeyeye (NUS, Singapore), with also large deformation characterizations.