Nanomechanical resonators operating as charge detectors in the nonlinear regime

We present measurements on nanomechanical resonators machined from silicon-on-insulator substrates. The resonators are designed as freely suspended Au/Si beams of lengths on the order of 1-4 mu m and a thickness of 200 nm. The beams are driven into nonlinear response by an applied modulation at radio frequencies;and a static magnet:ic field in plane. The strong hysteresis of the magnetomotive response allows sensitive charge detection by varying the electrostatic potential of a gate electrode.