Phase diagram of the A and B phases of superfluid 3He in aerogel

We report the first measurements of the A-B phase transition of superfluid He-3 confined within 98% silica aerogel in high magnetic fields and low temperatures. A disk of aerogel is attached to a vibrating wire resonator. The resonant frequency yields a measure of the superfluid Fraction p,lp of the He-3 within the aerogel. The inferred rho (s)/rho value increases substantially at the A-to-B transition of the confined superfluid, allowing us to map the A-B phase diagram as a function of held and temperature. At 4.8 bars, the B-T transition curve looks very similar to that in bulk with a simple reduction factor of order 0.45 for both transition field and temperature.