One-dimensional Excitations in Superfluid ${}^4$He and ${}^3$He-${}^4$He Mixture Films Adsorbed in Porous Materials

Abstract

A normal-fluid component varying as T${}^2$ is observed at very low temperatures in superfluid ${}^4$He and ${}^3$He-${}^4$He mixture films adsorbed in alumina powder. The normal fluid appears to arise from thermally excited third sound that has one-dimensional propagation characteristics. A Landau model of third sound excitations in an infinite cylindrical pore by Saam and Cole provides good agreement with the experimental measurements over a wide range of ${}^4$He and ${}^3$He coverages. However, it is unclear why the powder substrate can be modeled as having cylindrical pores.

arXiv comment5 pages, 6 figures, revtex4, to appear in PRB

References in corpus (1)

• Vortex Core Size in ${}^3$He-${}^4$He films with Monolayer Superfluid ${}^4$He