Spin correlations in Au-Fe alloys

Measurements of the (111) Bragg peak of ferromagnetic Au-Fe alloys reveal a remarkable three-step increase to saturation with decreasing temperature. The final “RKKY step” around ≈ 50 K is accompanied by broadening of the Bragg peak resulting in the observed q-dependent maxima in the low-q intensity. Viewed with increasing temperature the results suggest a continuous process of de-freezing of magnetic clusters of spins accompanied by “dynamic narrowing” of the Bragg peak.