The magnetic specific heat of spin-glass and ferromagnetic AuFe alloys between 2 and 300K

The magnetic specific heat Delta C of Au1-xFex has been determined between 2 and 300K from measurements of the difference in specific heat of pairs of Au1-xFex and Au1-xNx alloys. The concentration range investigated, 0.02 or=0.15). It is shown that the results provide evidence against substantial spatial short-range order but can be explained assuming a random distribution of Fe atoms. No discontinuity in Delta C is observed at the freezing temperature TF in the spin-glass and cluster-glass alloys, at which a susceptibility cusp has previously been observed, but TF is found to correlate well with a pronounced maximum in Delta C/T where the entropy is increasing most rapidly with temperature. The magnetic entropy is shown to be consistent with a spin between 1.2 and 1.5 for the Fe atoms.