Magnetic damping of a carbon nanotube nano-electromechanical resonator

A suspended, doubly clamped single-wall carbon nanotube is characterized at cryogenic temperatures. We observe specific switching effects in dc-current spectroscopy of the embedded quantum dot. These have been identified previously as nano-electromechanical self-excitation of the system, where positive feedback from single-electron tunneling drives mechanical motion. A magnetic field suppresses this effect, by providing an additional damping mechanism. This is modeled by eddy current damping, and confirmed by measuring the resonance quality factor of the radio-frequency-driven nano-electromechanical resonator in an increasing magnetic field. Nano-electromechanical resonator systems offer an intriguing field of research, where both technical applications and fundamental insights into the limits of mechanical motion are possible. Among these systems, carbon nanotubes offer the ultimate electromechanical beam resonator [1–3], because of their stiffness, low mass and high aspect ratio. At the same time, they are an outstanding material for transport spectroscopy of quantum dots at cryogenic temperatures [4, 5]. Chemical vapor deposition (CVD) has been shown to produce on chip defect-free single-wall carbon nanotubes [6]. By performing this growth process as the last chip fabrication step, suspended defectand contamination-free macromolecules can be integrated into electrode structures and characterized. On the electronic side, this has led to many valuable insights into, e.g., the physics of spatially confined few-carrier systems [7–9]. In terms of 1 Author to whom any correspondence should be addressed. New Journal of Physics 14 (2012) 083024 1367-2630/12/083024+08$33.00 © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft