One-dimensional Excitations in Superfluid He and He-He Mixture Films Adsorbed in Porous Materials
نویسندگان
چکیده
(Dated: February 1, 2008) A normal-fluid component varying as T is observed at very low temperatures in superfluid He and He-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 He and He coverages. However, it is unclear why the powder substrate can be modeled as having cylindrical pores.
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