title: Visualizing the Motion of Graphene Nanodrums.
abstract: Membranes of suspended two-dimensional materials show a large variability in mechanical properties, in part due to static and dynamic wrinkles. As a consequence, experiments typically show a multitude of nanomechanical resonance peaks, which make an unambiguous identification of the vibrational modes difficult. Here, we probe the motion of graphene nanodrum resonators with spatial resolution using a phase-sensitive interferometer. By simultaneously visualizing the local phase and amplitude of the driven motion, we show that unexplained spectral features represent split degenerate modes. When taking these into account, the resonance frequencies up to the eighth vibrational mode agree with theory. The corresponding displacement profiles, however, are remarkably different from theory, as small imperfections increasingly deform the nodal lines for the higher modes. The Brownian motion, which is used to calibrate the local displacement, exhibits a similar mode pattern. The experiments clarify the complicated dynamic behavior of suspended two-dimensional materials, which is crucial for reproducible fabrication and applications.
authors.affiliation: Kavli Institute of Nanoscience, Delft University of Technology , Lorentzweg 1, 2628 CJ, Delft, The Netherlands.
authors.forename: Dejan
authors.initials: D
authors.lastname: Davidovikj
authors.affiliation: Kavli Institute of Nanoscience, Delft University of Technology , Lorentzweg 1, 2628 CJ, Delft, The Netherlands.
authors.forename: Jesse J
authors.initials: JJ
authors.lastname: Slim
authors.affiliation: Kavli Institute of Nanoscience, Delft University of Technology , Lorentzweg 1, 2628 CJ, Delft, The Netherlands.
authors.forename: Santiago J
authors.initials: SJ
authors.lastname: Cartamil-Bueno
authors.affiliation: Kavli Institute of Nanoscience, Delft University of Technology , Lorentzweg 1, 2628 CJ, Delft, The Netherlands.
authors.forename: Herre S J
authors.initials: HS
authors.lastname: van der Zant
authors.affiliation: Kavli Institute of Nanoscience, Delft University of Technology , Lorentzweg 1, 2628 CJ, Delft, The Netherlands.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Steeneken
authors.affiliation: Kavli Institute of Nanoscience, Delft University of Technology , Lorentzweg 1, 2628 CJ, Delft, The Netherlands.|Quantified Air, Lorentzweg 1, 2628 CJ, Delft, The Netherlands.
authors.forename: Warner J
authors.initials: WJ
authors.lastname: Venstra
keywords: Graphene; NEMS; interferometry; mode shape