Spin-glass-like distribution of interaction fields in a nearly ferromagnetic Ni-Cu alloy

The magnetic specific heat (C_m) of a Ni-Cu alloy of 40 at% Ni was determined from low-temperature heat capacity measurements in various magnetic fields and is shown to derive from a dilute concentration of giant-moment clusters, consistent with previous magnetization measurements. From the field and temperature dependences of C_m, it is also deduced that the distribution of interaction (exchange and anisotropy) fields experienced by the clusters extends continuously from large positive fields to large negative fields, relative to the applied field.