372 research outputs found
Magnetic damping of a carbon nanotube NEMS 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 rf-driven nano-electromechanical resonator in
an increasing magnetic field.Comment: 8 pages, 3 figure
Strong feedback and current noise in nanoelectromechanical systems
We demonstrate the feasibility of a strong feedback regime for a
single-electron tunneling device weakly coupled to an underdamped single-mode
oscillator. In this regime, mechanical oscillations are generated and the
current is strongly modified whereas the current noise is parametrically big
with respect to the Poisson value. This regime requires energy dependence of
the tunnel amplitudes. For sufficiently fast tunnel rates the mechanical
contribution to current noise can exceed the Poisson value even beyond the
strong feedback regime.Comment: 4 pages, 3 figure
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