SPIN-WAVE VELOCITY, ENTROPY, AND MAGNETIZATION IN BCC SOLID HE-3

Precise measurements of the He-3 melting pressure in several magnetic fields have been made through the various magnetic ordering transition s. Throughout the low-field phase, we find a T4 temperature dependence of the melting pressure, characteristic of antiferromagnetic spin wav es with linear dispersion and a velocity of 7.8 cm/s, almost independe nt of field. However, the melting pressure in the high-field phase (HF P) deviates from the T4 dependence near the HFP-paramagnetic phase tra nsition, resulting in a very rapid entropy change near T(c). The spin- wave velocity increases with field, consistent with a strong temperatu re dependence of the magnetization. The entropy and magnetization disc ontinuities across the various phase boundaries have been determined. All results are thermodynamically consistent with the measured magneti c phase diagram.