SUPERFLUID-HELIUM ON SOLID HYDROGEN

Using third sound, we have found that helium atoms can form a superfluid in direct contact with the crystalline surface of solid hydrogen. An anomalous phase marked by a second line of transitions similar to the Kosterlitz-Thouless transition has also been discovered for thin superfluid films on the H-2 substrate for T < T(KT). This article compares these measured third sound velocities, in the ordinary superfluid phase, to a theoretical calculation, and the results from other work. The possible causes and interpretations for the new transition are discussed.