He3 has only 3/4 of the mass of He4. Hence,
The phase diagram of He3 is shown in 2 scales in Figs.3.17-8.
The minimum in the l-s coexistence curve in Fig.3.17 is due to the spin contribution to the entropy which makes change sign at . Since along the coexistence curve, the minimum follows directly from the Clausius- Clapeyron equation .
The superfluid phases (see Fig.3.18) appears only for so that they are not discernible in Fig.3.17. Since He3 is a fermion, a (Bose-Einstein) condensation into the superfluid phase requires a pairing mechanism. Depending on the angular momenta of the bounded pairs, different superfluid phases results.
1. The high temperature A-phase is anisotropic.
2. The low temperature B-phase is more or less isotropic.
3. A third phase appears under magnetic field.
4. Transition between normal & superfluid is continuous.
5. Transition between the A and B phases is 1st order.