From high-resolution measurements of the melting pressure of solid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ in applied fields, we determine the entropy and order of the magnetic phase transitions. We find the entropy discontinuity at the first-order antiferromagnetic transition to decrease as the field increases. No entropy discontinuity is seen at the paramagnetic to high-field transition, indicating that it is not first order.

• Received 21 April 1986

DOI:https://doi.org/10.1103/PhysRevLett.57.222