Metastability and Superfluid Fraction of the A-like and B Phases of 3He in Aerogel in Zero Magnetic Field.

We report the low-frequency sound measurements of the metastable A-like (A*) phase of superfluid ³He confined within a 98% open aerogel matrix in zero magnetic field. The second soundlike (slow) mode provides an accurate determination of the superfluid fraction of (and the transition between) the A* and B phases. The A* and B phases exhibit stable coexistence in the presence of disorder, the ratio of their superfluid fractions (ρ_a^A*/ρ_s^B) is much smaller than that of the bulk A and B phases, and argues that the A* and bulk A phases are distinct. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]