SKM 2021 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 7: Dielectric, Elastic and Electromechanical Properties
KFM 7.1: Vortrag
Mittwoch, 29. September 2021, 10:00–10:15, H1
Tunable Graphene Phononic Crystal — •Jan Niklas Kirchhof1, Kristina Weinel1,2, Sebastian Heeg1, Victor Deinhart2,3, Sviatoslav Kovalchuk1, Katja Höflich2,3, and Kirill I. Bolotin1 — 1Department of Physics, Freie Universität Berlin, Germany — 2Ferdinand-Braun-Institut, Berlin, Germany — 3Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany,
In the field of phononics, periodic patterning controls vibrations and thereby the flow of heat and sound in matter. Bandgaps arising in such phononic crystals (PnCs) realize low-dissipation vibrational modes and enable applications towards mechanical qubits, efficient waveguides, and state-of-the-art sensing. Here, we combine phononics and two-dimensional materials and explore tuning of PnCs via applied mechanical pressure. To this end, we fabricate the thinnest possible PnC from monolayer graphene and simulate its vibrational properties. We find a bandgap in the MHz regime, within which we localize a defect mode with a small effective mass of 0.72 ag = 0.002 mphysical. We exploit graphene’s flexibility and simulate mechanical tuning of a finite size PnC. Under electrostatic pressure up to 30 kPa, we observe an upshift in frequency of the entire phononic system by ∼ 350%. At the same time, the defect mode stays within the bandgap and remains localized, suggesting a high-quality, dynamically tunable mechanical system.