Description du sujet de thèse

Topological elastic metamaterials, situated at the intersection of condensed matter physics and materials science, are capable of hosting surface states protected by intrinsic topological properties, which opens new perspectives for controlling the propagation of elastic waves. The field of topological acoustic systems has seen rapid development since the demonstration of quantum Hall effects in acoustic media, followed by the realization of spin quantum Hall states and valley quantum Hall states. These fundamental advancements have paved the way for further research highlighting complex topological properties in acoustic and elastic metamaterials.
The TWEM project (Topological Wave Transport in Elastic Metamaterials), supported by the ANR (French National Research Agency), focuses on the demonstration of topological wave guiding through active control of the elastic wave injected into the structure. This approach, which involves adjusting the spatial and spectral properties of surface acoustic waves (SAWs) at GHz frequencies using a spatial light modulator, combined with picosecond acoustic techniques, allows precise control over the wave frequency and its spatial characteristics. These waves should provide accurate observations of interface modes, corner modes, and their stability in topological structures, especially at nano and submicron scales and GHz frequencies.
In this context, the objective of the PhD will focus on theoretical and numerical proposals and analyses of topological structures that go beyond the physical properties of robustness and unidirectionality to address the experimental constraints of chip integration for information transport. The limiting factors in the experimental study of topological devices at GHz scale are the generation, injection, and efficient control of elastic waves within complex metamaterial structures. At these frequencies, wave propagation is extremely sensitive to manufacturing imperfections, mode mismatches at interfaces, and energy losses due to reflections or dissipation, which makes it difficult to precisely explore topological protection and phononic transport.

Contexte de travail

The Institute of Electronics, Microelectronics, and Nanotechnology (UMR CNRS 8520 – website) is located in Villeneuve D'Ascq, near Lille (France). With a total staff of over 500 people, the institute has a broad research domain ranging from physics to materials science, micro, and nanotechnologies. The Ephoni group at IEMN, involved in this topic on the modeling side, has extensive expertise in the theoretical study of wave propagation in nanostructures/phononic, photonic, and plasmonic crystals. The EPHONI team, led by Y. Pennec, has contributed to the theoretical development of the field of phononic topological insulators since 2017.

Informations complémentaires

The candidate will contribute to the analysis and interpretation of data, manuscript preparation, and dissemination of results at national and international conferences/meetings. The candidate must hold a Master's degree in engineering, physics, or a similar field. Experience in numerical modeling is a plus.