Superfluid Onset and Compressibility of ${}^4$He Films Adsorbed on Carbon Nanotubes

Abstract

Third sound measurements of superfluid ${}^4$He thin films adsorbed on 10 nm diameter multiwall carbon nanotubes are used to probe the superfluid onset temperature as a function of the film thickness, and to study the temperature dependence of the film compressibility. The nanotubes provide a highly ordered carbon surface, with layer-by-layer growth of the adsorbed film as shown by oscillation peaks in the third sound velocity at the completion of the third, fourth, and fifth atomic layers, arising from oscillations in the compressibility. In temperature sweeps the third sound velocity at very low temperatures is found to be linear with temperature, but oscillating between positive and negative slope depending on the film thickness. Analysis shows that this can be attributed to a linearly decreasing compressibility of the film with temperature that appears to hold even near zero temperature. The superfluid onset temperature is found to be linear in the film thickness, as predicted by the Kosterlitz-Thouless theory, but the slope is anomalous, a factor of three smaller than the predicted universal value.

arXiv comment6 pages, 4 figures, revised version published in PRB

References in corpus (5)

• Phase diagram of 4He adsorbed on graphite
• Path integral Monte Carlo simulation of the second layer of helium-4 adsorbed on graphite
• Phase diagram of second layer of helium adsorbed on graphite
• Adsorption properties and third sound propagation in superfluid ${}^4$He films on carbon nanotubes
• Third sound measurements of superfluid ${}^4$He films on multiwall carbon nanotubes below 1K

Cited by in corpus (5)

• Layering transitions in superfluid helium adsorbed on a carbon nanotube mechanical resonator
• Superfluid Vortex Dynamics on Planar Sectors and Cones
• Analytical theory of enhanced Bose-Einstein condensation in thin films
• Supersolidity in the second layer of $para$-H${}_2$ adsorbed on graphite
• Fundamental connection between temperature-quenched 2D superfluids and 2D quantum turbulence