Quantum oscillations in a mechanical resonator containing a two dimensional electron system.

The temperature and magnetic field dependences of the resonant frequency and dissipation of a mechanical oscillator containing a two-dimensional electron system have been measured. At fixed temperature, the resonant frequency and dissipation both showed magnetic field dependent effects which corresponded to the Shubnikov-deHaas oscillations of delta sub (xx) measured on the same wafer. At low temperatures, 100mK, transport measurements showed well developed 4/3 and 5/3 states. No effects were seen with the oscillator in these states. We are presently studying the fractional states in more detail.