The magnetic specific heat Delta C of Au 1-x Fe x has been determined between 2 and 300K from measurements of the difference in specific heat of pairs of Au 1-x Fe x and Au 1-x N x alloys. The concentration range investigated, 0.02<or=x<or=0.23, includes the spin-glass, cluster-glass and ferromagnetic regimes. In addition to a linear electronic term at high temperatures for the more dilute alloys, the spin-glass and cluster-glass alloys (x<0.15) are characterised by a single broad maximum in Delta C at a temperature T G which increases only slowly with Fe concentration from 30 to 40K, and the authors conclude that the mean RKKY and nearest-neighbour ferromagnetic interactions are comparable in magnitude in this concentration region. An additional, sharper maximum in Delta C is observed at the ordering temperature T c in the ferromagnetic alloys (x>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 T F in the spin-glass and cluster-glass alloys, at which a susceptibility cusp has previously been observed, but T F 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.
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Mirza et al. (1985) studied this question.