Tunable Graphene Phononic Crystal
J.N. Kirchhof1, K. Weinel1,2, S. Heeg1, V. Deinhart2,3, S. Kovalchuk1, K. Höflich2,3, and K.I. Bolotin1
Published in:
Nano Lett., vol. 21, no. 5, pp. 2174-2182, doi:10.1021/acs.nanolett.0c04986 (2021).
Abstract:
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 toward 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 megahertz 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.
1 Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany
2 Ferdinand-Braun-Institut gGmbH, Leibniz-Institut für Höchstfrequenztechnik, 12489 Berlin, Germany
3 Helmholtz-Zentrum Berlin für Materialien und Energie, 14109 Berlin, Germany
Keywords:
Nanomechanics, phononic crystal, graphene, optomechanics, resonators, NEMS
© 2021 The Authors. Published by American Chemical Society.
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