Effects of ${}^4$He film on quartz tuning forks in ${}^3$He at ultra-low temperatures

Abstract

In pure superfluid ${}^3$He-B at ultra-low temperatures, quartz tuning fork oscillator response is expected to saturate when the dissipation caused by the superfluid medium becomes substantially smaller than the internal dissipation of the oscillator. However, even with small amount of ${}^4$He covering the surfaces, we have observed saturation already at significantly higher temperatures than anticipated, where we have other indicators to prove that the ${}^3$He liquid is still cooling. We found that this anomalous behavior has a rather strong pressure dependence, and it practically disappears above the crystallization pressure of ${}^4$He. We also observed a maximum in the fork resonance frequency at temperatures where the transition in quasiparticle flow from the hydrodynamic to the ballistic regime is expected. We suggest that such anomalous features derive from the superfluid ${}^4$He film on the oscillator surface.

arXiv comment9 pages, 5 figures

References in corpus (7)

• Quartz Tuning Fork: Thermometer, Pressure- and Viscometer for Helium Liquids
• Observation of half-quantum vortices in topological superfluid 3He
• Influence of Magnetic Scattering on Superfluidity of 3He in Nematic Aerogel
• Dry demagnetization cryostat for sub-millikelvin helium experiments: refrigeration and thermometry
• Mutual friction in superfluid ${}^3$He-B in the low-temperature regime
• Quartz Tuning Forks and Acoustic Phenomena - Application to Superfluid Helium
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• Suppressing the Kibble-Zurek mechanism by a symmetry-violating bias
• Topological nodal line in superfluid ${}^3$He and the Anderson theorem
• Performance of adiabatic melting as a method to pursue the lowest possible temperature in ${}^3$He and ${}^3$He-${}^4$He mixture at the ${}^4$He crystallization pressure
• Thermal conductivity of superfluid ${}^3$He-B in a tubular channel down to 0.1$T_c$ at the ${}^4$He crystallization pressure