Effects of Local Atomic Order on the Magnetic Properties of Au-25 at.% Fe

In a study of the effect of local atomic order on the physical properties of metallic solid solutions, the authors have measured changes in magnetic properties of a Au‐25 at.% Fe alloy with heat treatment. Measurements of σ were made as a function of H between 9.0 and 18.5 kOe and T between 78° and 320°K. The Curie temperatures were determined from plots of H/σ vs σ² and the magnetic moment at 0°K from an extrapolation of a plot of σ(18.5 kOe) vs $T^{\frac{3}{2}}$ . The local‐order parameters were determined for the two states from x‐ray diffuse scattering measurements. Application of the cluster‐variation method to the calculation of the Curie temperatures from the order parameters gives quantitative agreement with the experimental measurements, while the use of a Curie‐Weiss model gives values which are higher than experiment. The magnetic moments on the iron atoms are found to be higher than for pure iron and to increase with the change in order.