We have made torsional oscillator measurements of thin helium films on a Mylar surface preplated with 2 and 5 layers of H2. The minimum 4He coverage needed for superfluidity, or "inert" layer, n0 on both surfaces is found to be 6 μmole/m2. This is equivalent to 1/2 of a monolayer at bulk liquid density. The superfluid transition in coverages above n0 is similar to that found on bare Mylar, exhibiting the standard Kosterlitz-Thouless characteristics. We find no anomaly in ρs or the dissipation in the film that can be identified with a second transition reported in recent third sound experiments.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Materials Science(all)
- Condensed Matter Physics