Size effects in superfluid sup 3 He films

Journal Article · Fri Jun 01 00:00:00 EDT 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.41.11011· OSTI ID:6849583

Freeman, M R; Richardson, R C ^[1]

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1. Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853 (USA)

This paper addresses two related problems. One is the effect of small geometries on the superfluid phases of {sup 3}He, and the other is the nature of the scattering of {sup 3}He quasiparticles at surfaces. We perform measurements on 300-nm-thick films of {sup 3}He created by confining the liquid between closely spaced Mylar sheets. The fluid is probed simultaneously by two methods. Nuclear magnetic resonance monitors the spin dynamics of the system, yielding information with which we identify the superfluid phase. In this case, the liquid signal must be separated from that of the adsorbed surface layer, with which it is averaged by spin exchange. The hydrodynamic response of the fluid is determined from the period and damping of a torsion pendulum, which generates oscillatory motion of the substrate. In the normal and superfluid phases alike, this response is strongly dependent on microscopic details of the quasiparticle interactions with the surface. We compare the superfluid measurements to the Ginzburg-Landau model in which the order parameter vanishes at the walls (the diffusive boundary condition). Results for the superfluid transition temperature, the superfluid density, and the NMR frequency shift are in good quantitative agreement with the theory. Also in accord with the theory, we find that the superfluid {ital A} phase is stabilized by the walls over a wide range of pressures and temperatures at which the {ital B} phase is stable in bulk. In contrast with the calculations, however, we do not observe the {ital A}-{ital B} phase boundary. The {sup 3}He-substrate interface is modified in these experiments by the introduction of small quantities of {sup 4}He. {sup 4}He plates out preferentially on the surfaces at low temperatures, an effect that persists until a layer several atoms deep has been built up.

• OSTI ID: 6849583
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 41:16; ISSN 0163-1829; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CRITICAL SIZE
CRITICAL TEMPERATURE
ESTERS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FILMS
GINZBURG-LANDAU THEORY
HELIUM 3
HELIUM 3 A
HELIUM 3 B
HELIUM 4
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MATERIALS
MYLAR
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ORDER PARAMETERS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PHYSICAL PROPERTIES
PLASTICS
POLYESTERS
POLYMERS
QUASI PARTICLES
RELAXATION
RESONANCE
SIZE
SPIN-SPIN RELAXATION
STABLE ISOTOPES
SUPERFLUIDITY
SYNTHETIC MATERIALS
THERMODYNAMIC PROPERTIES
THIN FILMS
TRANSITION TEMPERATURE