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arXiv · 2111.05278

Fully suspended nano-beams for quantum fluids

Ilya Golokolenov·Baptiste Alperin·Bruno Fernandez·Andrew Fefferman·Eddy Collin
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Abstract

Non-invasive probes are keystones of fundamental research. Their size, and maneuverability (in terms of e.g. speed, dissipated power) define their applicability range for a specific use. As such, solid state physics possesses e.g. Atomic Force Microscopy (AFM), Scanning Tunneling Microscopy (STM), or Scanning SQUID Microscopy. In comparison, quantum fluids (superfluid $^3$He, $^4$He) are still lacking probes able to sense them (in a fully controllable manner) down to their smallest relevant lengthscales, namely the coherence length $\xi_0$. In this work we report on the fabrication and cryogenic characterization of fully suspended (hanging over an open window, with no substrate underneath) Si$_3$N$_4$ nano-beams, of width down to 50 nm and quality factor up to $10^5$. As a benchmark experiment we used them to investigate the Knudsen boundary layer of a rarefied gas: $^4$He at very low pressures. The absence of the rarefaction effect due to the nearby chip surface discussed in Gazizulin et al. [1] is attested, while we report on the effect of the probe size itself.

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Ilya Golokolenov, Baptiste Alperin, Bruno Fernandez, Andrew Fefferman, Eddy Collin. 2021-11-09. Fully suspended nano-beams for quantum fluids. https://doi.org/10.1007/s10909-022-02722-y

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