Superfluidity in /sup 3/He-/sup 4/He mixture thin films

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1980

OSTI ID:6237879

Webster, E

All results from our experiments studying superfluidity in /sup 3/He-/sup 4/He mixture films are presented. Our measurements spanned the temperature range from 1.3 to 1.8K, and up to 30% /sup 3/He molar concentration in the film. Films of up to 100 Angstroms thickness were studied. The experimental configuration and procedure are described. Relevant theories are reviewed. The areal superfluid mass density sigma/sub s/ is given in terms of an experimental measure of the film thickenss - sigma/rho(..beta..,T) - for all concentrations and temperatures studied. Detailed data from the onset regions are included. Precipitious onset phenomena were observed, and the Kosterlitz-Thouless-Nelson theory conclusively verified. However, no two-dimensional phase separation was observed, showing that mixture theories based on the X-Y model need additional refinement to correctly describe multilayer films. Experimental values of the superfluid onset and intercept (sigma/sub s/ extrapolated to zero) thicknesses of /sup 3/He-/sup 4/He mixture films are also exhibited. The latter (intercept) thickness is interpreted as a measure of the healing length, and alternatively as an excess normal fluid present in superfluid films. Analysis of our experimental evidence indicates that this excess normal fluid is due to surface roton excitations which exist at the substrate boundary, with an energy gap of 4.5/sup 0/K.

• Research Organization: California Univ., Los Angeles (USA)
• OSTI ID: 6237879
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DATA
DENSITY
DISPERSIONS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
FILM FLOW
FLUID FLOW
FLUIDS
HELIUM 3
HELIUM 4
HELIUM II
HELIUM ISOTOPES
INFORMATION
ISOTOPES
LIGHT NUCLEI
MIXTURES
NUCLEI
NUMERICAL DATA
PHYSICAL PROPERTIES
QUANTUM FLUIDS
SOLUTIONS
STABLE ISOTOPES
SUPERFLUIDITY
ULTRALOW TEMPERATURE