This review describes sound propagation in the normal state and the superfluid B phase of 3He. The l=1 nature of Cooper pairing in superfluid 3He leads to a complex collective mode spectrum. A number of the collective modes couple to sound. The expressions for the collective mode frequencies are derived using a phenomenological theory. Cryogenic and ultrasonic measurement techniques are briefly discussed, followed by a review of the results of sound propagation experiments, in particular those that show coupling to the collective modes. The effects of fields, textures and dispersion are also reviewed.
ASJC Scopus subject areas
- Condensed Matter Physics