Tunable Graphene Phononic Crystal

In the field of phononics, periodic patterning controls vibrations and thereby flow heat sound in matter. Bandgaps arising such phononic crystals realize low-dissipation vibrational modes enable applications towards mechanical qubits, efficient waveguides, state-of-the-art sensing. Here, we combine phononics two-dimensional materials explore possibility manipulating via applied pressure. To this end, fabricate thinnest possible crystal from monolayer graphene simulate its properties. We find a bandgap MHz regime, within which localize defect mode with small effective mass 0.72 ag = 0.002 $m_{physical}$. Finally, take advantage graphene's flexibility mechanically tune finite size crystal. Under electrostatic pressure up to 30 kPa, observe an upshift frequency entire system by more than 350%. At same time, stays remains localized, suggesting high-quality, dynamically tunable system.