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Superfluidity in reduced dimensionality systems

Thesis/Dissertation ·
OSTI ID:6487337
The superfluid density for He/sup 4/ films adsorbed in two different geometries has been studied. With Vycor glass, using a third sound technique, phonons with a T/sup 2/ temperature dependence have been observed. These are attributed to the cylindrical nature of the Vycor pores. Also observed were rotons with a 5 K energy gap. The observations were in substantial agreement with calculations by Padmore and others for two-dimensional rotons. Also studied were He/sup 4/ films adsorbed in porous Vycor glass near their critical points using an Andronikashvili method. The superfluid density was found to vary as a power law in reduced temperature with an exponent equal to the bulk value. This three-dimensional critical behavior was attributed to the three-dimensional interconnectedness of the Vycor substrate. For He/sup 4/ films using a Mylar substrate with an Andronikashvili method, profound differences in the nature of the superfluid transition have been observed. A sharply changing superfluid density at the transition was seen along with a peak in the superfluid dissipation. By interpreting the data through a dynamic theory, the Kosterlitz-Thouless picture of superfluidity in two dimensions was supported. Good numerical agreement with the universal constant predicted by the theory was obtained.
Research Organization:
Cornell Univ., Ithaca, NY (USA)
OSTI ID:
6487337
Country of Publication:
United States
Language:
English

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Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ADSORPTION
DATA
DENSITY
ENERGY GAP
ESTERS
EVEN-EVEN NUCLEI
EXPERIMENTAL DATA
FLUIDS
HELIUM 4
HELIUM II
HELIUM ISOTOPES
INFORMATION
ISOTOPES
LIGHT NUCLEI
MATERIALS
MYLAR
NUCLEI
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PLASTICS
POLYESTERS
POLYMERS
QUANTUM FLUIDS
SORPTION
STABLE ISOTOPES
SYNTHETIC MATERIALS
TEMPERATURE DEPENDENCE
VYCOR