Prof. Dr. Herre van der Zant
(Technical University Delft)
PGI Lecture Hall, Building 04.8, 2nd floor, Room 365
- 11.Jul.2014 11:00
Nano-electromechanical systems (NEMS) make use of electrically induced mechanical motion and vice versa. Carbon nanotubes and atomically thin membranes are ideal building blocks of NEMS because of their unique (mechanical) properties and their low mass. This puts them in an unexplored regime of motion which approaches the fundamental detection limit set by quantum mechanics (see e.g. Mechanical systems in the quantum regime, M. Poot and H.S.J. van der Zant, Physics Reports 511 (2012) 273). At room temperature, we use mixing techniques to probe the bending-mode vibration of a suspended carbon nanotube; the gate voltage strains the carbon nanotube and thereby tunes its frequency. At low temperatures, mechanical vibrations are actuated by a nearby antenna and a Q-value of 150000 at a resonance frequency of 300 MHz is achieved. With scanning-probe techniques the mechanical properties of atomically thin membranes can be measured. Resonant behaviour is usually probed by electrical means or interferometer set-ups. Due to their small cross-sections nonlinear effects are easily observed: carbon-based resonators behave as floppy systems. An open issue is the low quality of the membranes at room temperature. Ring-down measurements show that the Q-value is determined by intrinsic dissipation mechanism and not by spectral broadening.
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