Kosterlitz-Thouless superfluid transition for thin helium-4 films adsorbed in porous media

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5973247

Kotsubo, V Y

Thin helium-4 films adsorbed in porous media with small grain sizes are studied in an attempt to understand size effects on the thin-film superfluid transition. Films were adsorbed in 500A, 3000A, and 1..mu.. diameter packed alumina powders, and the superfluidity density was probed using third sound. The main features observed are a broadening of the transition and a reduction of third sound attenuation as the grain sizes are reduced. To explain the results, the flat-substrate Kosterlitz-Thouless theory is adapted to a finite-size system. The model, which is based on the behavior of thermally excited vortices, qualitatively agrees with the experimental results. Fits to the sound velocity data produces reasonable values for the parameters of the vortices, but quantitative agreement with the attenuation data could not be achieved. The overall results of this study suggests that the transition evolves continuously as the geometry changes form the flat substrate down to this small scale systems.

• Research Organization: California Univ., Los Angeles (USA)
• OSTI ID: 5973247
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
EVEN-EVEN NUCLEI
FILMS
HELIUM 4
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
MATERIALS
NUCLEI
POROUS MATERIALS
STABLE ISOTOPES
SUPERFLUIDITY
THIN FILMS
THIRD SOUND