Periodic Reporting for period 4 - TopMechMat (Topological Mechanical Metamaterials)
Período documentado: 2022-08-01 hasta 2023-01-31
By overcoming this challenge, we will be able to provide materials engineers with design templates that allow them to fabricate a large variety of devices. Possible applications are signal filters for WiFi and 5G communications that allow for more bandwidth at lower power levels. Other applications could be enhanced vibration isolation of large industrial facilities to reduce noise emission, or in contrast, intelligent energy harvesting out of environmental noise. Just about anything that requires exquisit control of how waves travel through materials.
The overall objective is to further our basic understanding of topological band theory in the context of classical vibrations. Once we harness this design tool, the aforementioned device application could become available.
In conclusion, we have made significant strides in metamaterial design. Methodologically, we have developed a new optimization strategy for mechanical metamaterials adept at tackling the aforementioned challenges. By employing a modern evolutionary strategy (CMA-ES) to design material structures, we integrated the intricate cost functions essential for embedding large-scale functionality within microscopic material design. With this innovative, data-driven approach, we have managed to overcome various technological hurdles. As evidence, we present several scientific breakthroughs, including the first observation of a higher-order topological insulator, the first realization of band structures with an axial magnetic field, and the pioneering experimental characterization of a fragile topological system. The last discovery is especially noteworthy, as this type of topology could be central to superconductivity in twisted bi-layer graphene—a current enigma in condensed matter physics. On the application front, our project demonstrates how a passive mechanical structure, designed using our tools, can act as a binary classifier for spoken words. This last endeavor vividly illustrates the potential of mechanical metamaterials as intelligent yet passive sensors.
The results can be summarized as follows: Six key publications highlight our principal accomplishments. In a 2018 Nature article, we utilized the preliminary version of our theoretical framework and design methodology to craft a vibrational structure that showcased a topological effect. This effect had only been predicted a year earlier and had not been observed in any other platform. In 2019, we conducted the first controlled experiment in which synthetic axial magnetic fields induced chiral Landau levels; this work was published in Nature Physics. In 2020, our research focused on the experimental characterization of the spectral flow in a fragile band, and the findings were featured in Science. Building on the insights from this Science article, we enhanced our understanding of the exotic superconductivity in twisted bi-layer graphene. This led to two publications in Physical Review Letters in 2021 and 2022, respectively.