A Mossbauer study of the magnetic properties of CuFe alloys

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Abstract
The Mossbauer effect has been used to investigate the magnetic properties of Cu-Fe alloys of concentration 0.24-4.6% Fe in the temperature range 4.2-100K and in applied magnetic fields of up to 8.0 T. Alloys containing more than about 0.5% Fe exhibited magnetic broadening at 4.2K and the transition temperatures at which the broadening first occurred have been determined. The distributions of hyperfine magnetic fields observed in these specimens below the transition temperatures have been studied as functions of iron concentration and of temperature. The saturation hyperfine fields for isolated iron atoms are found to vary with concentration, exhibiting a linear variation at high concentrations but falling more rapidly at lower concentration. This is interpreted as evidence for the formation of a Kondo state. Spectra obtained at high magnetic fields indicate some anisotropy in the impurity response to the applied field.