X-ray determination of atomic short-range order in the spin-glass systemAuFe

Diffuse x-ray measurements carried out on $\mathrm{Au}\mathrm{Fe}$ single crystals of 14.4, 15.4, and 19 at.% Fe show evidence for short-range order quite different in nature from that found in $\mathrm{Ag}\mathrm{Mn}$ and $\mathrm{Cu}\mathrm{Mn}$ alloys. This short-range order is seen as (1) a strong small-angle scatterings suggesting a tendency towards segregation, (2) a system of diffuse streaks extending in a discontinuous manner along $〈1\frac{1}{2}0〉$ axes and equivalents, and (3) an asymmetry of the diffuse streaks about each Bragg spot. We interpret this ensemble of facts by the existence of Fe-rich platelets oriented parallel to {420} planes, about two-planes thick and extending 30 Å parallel to their plane.