Magnetization cusp in a thin AuFe spin glass film in high magnetic fields

Abstract

We performed polarized neutron reflectometry measurements on a 78 nm-thick Au 97Fe 3 film prepared on a thermally oxidized Si wafer. The measurements were done on the C5 spectrometer at Chalk River in reflectometry mode. We determined the magnetization of the specimen in a vertical magnetic field of 6 T in a temperature range from 300 to 1.5 K. We observed a cusp in the magnetization at about 10 K, close to the spin-glass freezing temperature of 16 K of a bulk Au 97Fe 3 alloy. From the fit to the reflectivity data we can infer a magnetic moment of 0.63 μ B per Fe atom at the cusp position which is a large reduction compared to the bulk value of 1.2 μ B per Fe atom.