Layering Transition in Superfluid Helium Adsorbed on a Carbon Nanotube Mechanical Resonator

Abstract

Helium is recognized as a model system for the study of phase transitions. Of particular interest is the superfluid phase in two dimensions. We report measurements on superfluid helium films adsorbed on the surface of a suspended carbon nanotube. We measure the mechanical vibrations of the nanotube to probe the adsorbed helium film. We demonstrate the formation of helium layers up to five atoms thickness. Upon increasing the vapour pressure, we observe layer-by-layer growth with discontinuities in both the number of adsorbed atoms and the speed of sound in the adsorbed film. These hitherto unobserved discontinuities point to a series of first-order layering transitions.Our results show that helium multilayers adsorbed on a nanotube are of unprecedented quality compared to previous works. They pave the way to new studies of quantized superfluid vortex dynamics on cylindrical surfaces, of the Berezinskii-Kosterlitz-Thouless phase transition in this new geometry, perhaps also to supersolidity in crystalline single layers as predicted in quantum

Superfluid and Supersolid Phases ofHe4on the Second Layer of Graphite

“…The light mass of Helium atoms and the strong Carbon-Helium interaction make 4 He adsorbed on graphite the most paradigmatic example of a twodimensional (2D) quantum system. Its phase diagram was extensively studied in the 90s, using a variety of experimental techniques (see, for instance, Ref.…”

Superfluid vortex dynamics on planar sectors and cones

“…In the two limits, we have shown explicitly that the results presented here reproduce those well-known behaviors. As a final remark, we note that our previous results on cylindrical surfaces may prove very useful to understand the physics at play in the very recent experiment that studied superfluid 4 He adsorbed on carbon nanotubes [13,14]. edges support from Spanish MINECO (FIS2017-84114-C2-1-P) and the "Ramón y Cajal" program.…”

Atomically Layered Helium Films at Ultralow Temperatures: Model Systems for Realizing Quantum Materials

“…Experimentally, there are multiple issues: contamination of the graphene surface and requirement for new measurement techniques tailored to measurements on samples with small surface area. The growth of helium films on a nanotube operated as a nanomechanical resonator has recently been demonstrated, with evidence of first-order layering transitions which testify to substrate quality [134]. Elsewhere the sensitivity of electrical transport through a carbon nanotube to a variety of adsorbates, including helium, has been demonstrated [135][136][137].…”