Abstract
Suspended aluminum nanoelectromechanical resonators have been fabricated, and the manufacturing process is described in this work. Device motion is driven and detected with a magnetomotive method. The resonance response has been measured at 4.2 K temperature in vacuum and low-pressure ^4hbox {He} gas. At low oscillation amplitudes, the resonance response is linear, producing Lorentzian line shapes, and Q values up to 4400 have been achieved. At higher oscillation amplitudes, the devices show nonlinear Duffing-like behavior. The devices are found to be extremely sensitive to pressure in ^4hbox {He} gas. Such device is a promising tool for studying properties of superfluid helium.
Highlights
In cryogenic fluids like 4He and 3He, immersed oscillating objects such as tuning forks, wires, grids and spheres have proven to be useful and multifunctional tools acting as thermometers, bolometers, pressure gauges, viscometers, as well as generators and detectors of turbulence, cavitation and sound [1,2,3,4]
Fluid properties are usually determined from measured changes in mechanical resonance response including resonance frequency, line width, amplitude and certain nonlinear effects
Numerical finite element method simulations (COMSOL) show that the first eigenmode of the nanomechanical resonator corresponds to out-of-plane and in-phase oscillation of the two cantilever feet connected by a rigid paddle
Summary
In cryogenic fluids like 4He and 3He, immersed oscillating objects such as tuning forks, wires, grids and spheres have proven to be useful and multifunctional tools acting as thermometers, bolometers, pressure gauges, viscometers, as well as generators and detectors of turbulence, cavitation and sound [1,2,3,4]. Journal of Low Temperature Physics (2019) 196:283–292 vortex-core-bound fermions in the vortex dynamics in 3He-B [11,12]; vortex friction due to the chiral anomaly, and the synthetic electromagnetic fields created by vortex motion in Weyl superfluid 3He-A [13]. To reach this goal, we have fabricated suspended aluminum nanoelectromechanical (NEMS) resonators with typical effective mass ∼ 10 pg, dimensions ∼ 10 μm and rectangular cross section of 150 nm×1.1 μm (see Fig. 1). The geometry allows for relatively low resonance frequency, which is an important factor in keeping damping due to acoustic emission in superfluids small [15]
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