Search for weak random anisotropy effects in the critical region of Pd80Co20

Following a suggestion by I. A. Campbell, we have conducted Mossbauer source experiments on disordered alloys of57CoPd80Co20 in search for evidence of random anisotropy (RA) effects on critical behavior. The result, β=0.38(3) in the reduced temperature range 10−2<1−T/Tc<0.2, though not strictly asymptotic, is consistent with the d=3 Heisenberg model, with no evidence for RA. In this paper we argue that among transition metal ferromagnetic alloys there are no better candidates for RA effects than our chosen system.