105 / 168
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.
105