^{Circular nanoelectromechanical resonators based on hexagonal boron nitride graphene heterostructures}

2D materials like graphene and h-BN, to name a few, when layered on top of each other offer a new class of metamaterials. Especially, the twisting degree of freedom between two layers has opened the window for new phenomenon not explored before. The mechanical properties of these heterostructures in the form of nanoelectromechanical systems (NEMS) have not been studied extensively. Their exceptional attributes like ultra-low mass, robustness and high tunability make 2D materials suitable for NEMS which holds promise for various technological applications viz. ultrafast sensors, actuators etc. We report fabrication and characterization of hexagonal-boron nitride (h-BN) graphene heterostructure based circular nanoelectromechanical resonators on sapphire substrates. The device is measured at cryogenic temperatures and exhibits multiple mode frequencies which are highly tunable with gate voltage. A continuum mechanics model is employed to analyze the transmission (S₂₁) data of fundamental mode. Parameters like built-in tension obtained from the fit are used to identify the indices (m, n) of higher mechanical modes observed for the device. NEMS could offer a way to study the electronic phenomena such as superconductivity in twisted bilayer graphene heterostructures.