Specific-Heat Anomaly and Phase Boundary for the Spin-Glass-Paramagnet Transition inCuMn

Measurements on 2790-at.-ppm $\mathrm{Cu}\mathrm{Mn}$ between 0.3 and 30 K and in fields to 75 kOe show a small, field-dependent specific-heat anomaly that is, apart from magnitude, in qualitative agreement with recent theoretical predictions for the spin-glass transition. The results support the approximate validity of mean-field theory for real spin-glasses, and, indirectly, the reality of the predicted phase transition. The field dependence of the entropy is compared with the Parisi-Toulouse projection hypothesis.