QFS2016 Book of Abstracts

Abstracts

I4.1 Nanomechanical beams for sub-coherence length studies in superfluid 3 He Eddy Collin (speaker), R. Gazizulin, O. Maillet, A. Fefferman Institut N´eel/CNRS and Universit´e Grenoble Alpes, 38042 Grenoble, France Mechanical probes such as vibrating wires and forks are neat devices for the studies of quantum fluids. The coherence length of superfluid 3 He is of the order of 100 nm, a lengthscale which is easily attained today using clean room fabrication: it is thus possible now to probe this scale using dedicated nano-electro-mechanical systems (NEMS). We present low temperature properties of these devices, both linear and non-linear, and introduce measuring techniques. In particular, the parametric amplification scheme is extremely useful for over-damped systems. We discuss preliminary fluid dynamics measurements using NEMS of cross dimensions about 100 nm, and lengths up to 300 microns. O4.1 Nanomechanical double clamped beam for probing quantum fluids. Bradley D.I., George R., Haley R.P., Kafanov S., Pashkin Yu.A., Pickett G.R., Poole M., Prance J.R., Schanen R., Sarsby M., Tsepelin V., Wilcox T. Lancaster University, Department of Physics, Lancaster LA1 4YB, United Kingdom Vibrating wires and quartz tuning forks are well known and developed tools to probe the properties of normal and superfluid helium. They enable the study of helium properties in the frequency range from DC to about 300 kHz. We have developed a fabrication method for nanoelectromechanical systems (NEMS), that permits the creation of aluminium doubly clamped suspended nanowires with cross-sectional dimensions of 100nm x 100nm. This size is comparable to the superfluid helium-4 penetration depth, and opens up investigation of the properties of quantum fluids on a shorter length scale. The extremely broad range of available lengths of nanowires, from 0 . 5 µm up to 500 µm , provides the possibility to cover the frequency range from tens of kHz up to hundreds of MHz. We present novel results probing gaseous, normal fluid and superfluid helium-4 using these vibrating nanowires. The observed behaviour of the nanowires immersed in helium-4 can be explained with a hydrodynamic damping in the framework of the two fluid model.

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