SUPERFLUIDITY WITHOUT SUPERFLOW IN UNSATURATED HELIUM FILMS

It is shown experimentally that the superfluid fraction ρsρ is continuous and finite at the point at which superflow vanishes in unsaturated helium films. It follows that there is a region of superfluidity without superflow. In addition it is shown that the behavior of the partial molar entropy may account for the disappearance of superflow without requiring that ρsρ vanish. © 1969 The American Physical Society.