The onset of superfluidity in thin films of {sup 4}He adsorbed on ordered and disordered substrates
The authors have completed a systematic study of the superfluid density of {sup 4}He films adsorbed on two substrates: exfoliated basal-plane graphite and 91% porosity aerogel glass. The authors measurements demonstrate a dramatic difference in the coverage-dependence of the superfluid density in these two systems. The onset of superfluidity in the aerogel system is similar to that observed in the case of other disordered substrates such as Vycor glass and mylar. The superfluid density at zero temperature is nearly proportional to coverage once the critical coverage for superfluidity is exceeded. The superfluid density for films adsorbed on graphite does not evolve in this simple fashion. The onset of superfluidity appears to occur near two layers, but the superfluid density increases very rapidly between 2.5 and 3 layers. This coverage regime is also characterized by a dramatic sharpening density and transition temperature remain essentially unchanged as the coverage is increased. We will discuss in the context of recent theoretical work on the onset of superfluidity in model Bose systems.
- OSTI ID:
- 243903
- Report Number(s):
- CONF-9304297--; CNN: Grant DMR-8921733; Grant DMR-91654
- Journal Information:
- Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 2 Vol. 38; ISSN 0003-0503; ISSN BAPSA6
- Country of Publication:
- United States
- Language:
- English
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