Magnetization measurements for AuFe spin-glass alloys in fields up to 40 T

High-field magnetization curves are presented for AuFe alloys of Fe concentrations: c = 3.1, 5.1, 6.5 and 10.4 at.%, at T = 4.2 K in pulsed fields up to 40 T. For c = 10.4 at.% additional data were taken at T = 1.2 K and 77 K. From these results we conclude that the nearest-neighbour interaction between the Fe atoms in Au is ferromagnetic, of order of 80 K. The behaviour of the magnetization curves can be qualitatively explained in terms of ferromagnetic clusters that are antiferromagnetically coupled.