Bistability and oscillatory motion of graphene nano-membranes on silicon dioxide

The truly two-dimensional material graphene is an ideal candidate for nanoelectromechanics due to its large strength and high electron mobility. Here, we show that a monolayer of graphene on SiO$_2$ provides natural, ultra-small membranes of diameters down to 3\,nm within its intrinsic rippling. These membranes can be lifted either reversibly or hysteretically by the tip of a scanning tunneling microscope (STM). The clamped-membrane model including van-der-Waals and dielectric forces explains the results quantitatively. Application of an AC-voltage oscillates the nanomembrane, which might lead to a completely novel approach to controlled quantized oscillations or single atom mass detection.