Phase diagram for some 3He-4He mixture films from third-sound experiments

Third-sound velocity measurements in 3He-4He mixture films are used to obtain the phase diagram for different coverages. The characterization of these films is discussed, and a correct parameters choice is proposed. Using a rough estimate of the superfluid density, we find that at the superfluid transition temperature the same universal feature as in 4He film is observed. The general behavior of our films is, however, not similar to theoretical predictions for two-dimensional mixtures, and the phase separation is not detected. New experiments are suggested by our results in order to clarify the behavior of mixture films