2026-08-11T10:24:33Zhttps://www.radar-service.eu/oai/OAIHandler

10.35097/17542024-06-20T09:23:24Z3DMM2Oradar4kit

10.35097/1754 Chen, Yi Yi Chen 0000-0002-6614-976X Karlsruhe Institute of Technology Groß, Michael Michael Groß 0000-0003-2611-4172 Karlsruhe Institute of Technology Schneider, Jonathan Jonathan Schneider 0009-0000-5707-7189 Karlsruhe Institute of Technology Karlsruhe Institute of Technology 2023 2023 Physics Materials Science Engineering Open Access Creative Commons Attribution 4.0 International KIT In many cases, the hybridization of two or more excitation modes in solids has led to new and useful dispersion relations of waves. Well-studied examples are phonon polaritons, plasmon polaritons, particle-plasmon polaritons, cavity polaritons, and magnetic resonances at optical frequencies. In all of these cases, the lowest propagating mode couples to a finite-frequency localized resonance. Herein, the unusual metamaterial phonon dispersion relations arising from the hybridization of an ordinary acoustical phonon mode with a back-folded soft or easy phonon mode of a monomode elastic metamaterial are discussed. Conceptually, the single easy mode can have strictly zero wave velocity. In reality, its wave velocity is very much smaller than that of all other modes. Considering polymeric 3D printed elastic monomode metamaterials at ultrasound frequencies, it is shown theoretically and experimentally that the resulting pronounced avoided crossing, with a frequency splitting comparable to the mid-frequency, leads to backward-wave behavior for the lowest band over a broad frequency range, conceptually at zero loss. 10.1002/adma.202307553 Deutsche Forschungsgemeinschaft (DFG) 0000 0001 2096 9829 EXC 2082 - 390761711 3D Matter Made to Order (3DMM2O) application/x-tar