Superfluidity in pure sup 4 He and sup 3 He- sup 4 He mixture films

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5149654

McQueeney, D F

The author used a torsional oscillator technique to measure the superfluid density in a wide range of two dimensional systems. Both pure {sup 4}He and {sup 3}He-{sup 4}He mixture films were studied. Three experimental cells with different substrates were employed, one of which had a two dimensional geometry while the other two were three dimensionally interconnected porous media. He finds that the Kosterlitz-Thouless theory provides a good description of the basic physics of the superfluid transition in each of the systems studied, and the Nelson-Kosterlitz prediction of a universal superfluid jump is obeyed over the observed range of experimental parameters. A comparison of the data with finite frequency extensions to the Kosterlitz-Thouless theory shows that the details vortex dynamics in thin films of {sup 4}He cannot be understood on the basis of the finite frequency theory alone. He proposes a phenomenological model of film thickness variations to explain the results. The first quantitative measurements of the interfacial superfluid system formed by a {sup 3}He-{sup 4}He mixture in the presence of a confining wall are presented. He finds that the two dimensional superfluid is remarkably robust, with only the thinnest films having their transition temperature suppressed by additions of {sup 3}He. Bulk-like solution effects dominate the observed superfluid density at finite temperatures. At T = O, the effect of {sup 3}He on the superfluid is to produce an additional 1/2 monolayer of normal {sup 4}He at the {sup 3}He-{sup 4}He interface. The superfluid density in two different three dimensionally interconnected porous media is discussed.

• Research Organization: Cornell Univ., Ithaca, NY (USA)
• OSTI ID: 5149654
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COMPARATIVE EVALUATIONS
DENSITY
DIMENSIONS
DISPERSIONS
DYNAMICS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FILMS
GLASS
HELIUM 3
HELIUM 4
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
MATERIALS
MATHEMATICAL MODELS
MECHANICS
MIXTURES
NUCLEI
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
POROUS MATERIALS
STABLE ISOTOPES
SUBSTRATES
SUPERFLUIDITY
THERMODYNAMIC PROPERTIES
THICKNESS
THIN FILMS
TRANSITION TEMPERATURE