A Tunable Hybrid Electro-magnetomotive NEMS Device for Low Temperature Physics

Microfabrication techniques have made possible the realization of mechanical devices with dimensions in the micro- and nano-scale domain. At low temperatures, one can operate and study these devices in well-controlled conditions, namely low electrical noise and cryogenic vacuum, with the ability to use high magnetic fields and superconducting coating metals (Collin et al. in J. Low Temp. Phys. 150(5-6):739, 2008). Moreover, the temperature turns out to be a control parameter in the experimental study of mechanical dissipation processes, with the cryogenic environment ensuring that only low energy states are thermally populated. Immersed in a quantum fluid, these MEMS and NEMS devices (micro and nano electro-mechanical systems) can probe the excitations of the liquid at a smaller scale, with higher frequencies and better resolution than "classical" techniques (Triqueneaux et al. in Physica B 284:2141, 2000). We present experimental results obtained in vacuum on cantilever NEMS structures which can be both magnetomotive and electrostatically driven. The device is extremely sensitive with resolved displacements down to 1 using conventional room-temperature electronics. It is calibrated in situ, and frequency/non-linearity can be tuned electrostatically. The design should allow parametric amplification to be used.