Magnetic correlations in an amorphous Gd-Al spin glass

Small-angle neutron scattering (SANS) as well as magnetization measurements have been made on a sputtered film of Gd43Al 57. The low field susceptibility peaks at a freezing temperature Tf of 33 K. This agrees well with the SANS data, which shows a peak in the intensity at this temperature for the lowest Q's measured. The SANS line shapes are unusual in that they can be fitted with a Lorentzian plus Lorentzian-squared cross section with dissimilar correlation lengths. The Lorentzian correlation length peaks near 35 K at a value of ∼14 Å, while the Lorentzian-squared correlation length exhibits a large, essentially resolution-limited, value up to temperatures several times Tf. These results are consistent with the coexistence of finite static spin clusters with relatively long-range ferromagnetic correlations.