External control of dissipation in a nanometer-scale radiofrequency mechanical resonator

We demonstrate a technique by which the quality factor of a magnetically-actuated mechanical resonator is controlled by an external electrical circuit. Modulation of this parameter is achieved by local variation of the electrical impedance presented to the resonator at its resonance frequency. We describe a theory that explains this result as arising from eddy currents in the external electrical circuit, which are driven by electromotive forces generated through motion of the resonator in the applied magnetic field. The theory is in good agreement with the induced variation in quality factor that we observe. q 1999 Elsevier Science S.A. All rights reserved.