Evidence for two superfluid transitions in He3-He4 films

Two superfluid phase transitions in He3-He4 films have been observed. Both transitions, A and B, possess Kosterlitz-Thouless characteristics, but phase B has a much less pronounced onset signal. At constant He4 coverage the transition temperature of A decreases while that of B increases upon addition of He3. We discuss possible interpretations of these results based on existing theories and connections with other measurements.