Some new observations at the superfluid transition in 3He–4He films

Abstract

We have studied quasi two-dimensional 3He–4He mixtures by means of a high-Q torsional oscillator. In contrast to the case of pure 4He films, two superfluid phase transitions have been observed in mixture films where the 4He coverage is near one active layer. For a somewhat larger coverage of 4He, the addition of 3He causes the superfluid transition to shift, at first, to higher temperatures rather than lower ones as is usually observed.