Calorimetric Investigation of Spin-Glass Ordering in CuMn

New measurements near Tsg characterize the heat capacity anomaly associated with spin-glass ordering. There are no discontinuities in the heat capacity or its temp. or field derivatives but there is a relatively sharp anomaly in the field derivative and a broad anomaly in the temp. derivative. A failure of thermodynamics to predict correctly the relation between heat capacity and magnetic susceptibility may be a manifestation of the @nonergodic@ behavior of disordered systems.17 refs.--AA