Tunable coupling of two mechanical resonators by a graphene membrane

Abstract

Coupled nanomechanical resonators are interesting for both fundamental studies and practical applications as they offer rich and tunable oscillation dynamics. At present, the mechanical coupling in such systems is often mediated by a fixed geometry, such as a joint clamping point of the resonators or a displacement-dependent force. Here we show a graphene-integrated electromechanical system consisting of two physically separated mechanical resonators-a hybrid graphene comb-drive actuator system and a suspended silicon beam-that are tunably coupled by the integrated graphene membrane. The graphene membrane, moreover, provides a sensitive electrical read-out for the two resonating systems showing 16 different modes in the frequency range from 0.4 to 24 MHz. In addition, by pulling on the graphene membrane with an electrostatic potential applied to silicon beam resonator, we control the mechanical coupling, quantified by the g-factor, from 20 kHz to 100 kHz. Our results pave the way for coupled nanoelectromechanical systems requiring controllable mechanically coupled resonators.

Dynamics of 2D material membranes

“…Typically, values of ∆ω are in the 0.1-10 kHz range to avoid lowfrequency noise. Several works have demonstrated this downmixing technique in 2D materials resonators [57,82]. A potential drawback of mixing techniques is that the sideband signal may cause crosstalk and may also actuate the drum [14], in particular when ∆ω < ωm 2Q .…”

“…Similarly, cooling down the material changes the tension, which can be used to study material properties like thermal expansion (see section 6.1.3). Even more accurate control over tension is obtained using MEMS actuators (figures 6(c) and (d)), which can tune 2D material resonance frequencies over a range of more that 10% [82,117].…”

Nanomechanical vibrational response from electrical mixing measurements

“…The electrical mixing detection has been applied to resonators based on carbon nanotubes [6,10,12,28,[30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46], graphene [35,[47][48][49][50][51][52][53][54][55][56][57], transition metal dichalcogenides (TMDs) [58][59][60][61][62][63], and semiconducting nanowires [64][65][66][67][68][69][70][71]. Different variants of the mixing method were developed by applying either two signals [28] on the device or one signal that is amplitude [48] or frequency…”