Onset of magnetism in iron-chromium glasses

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Abstract
Mössbauer spectra at 4.2 K of (Fex Cr100−x) By metallic glasses with 50≤x≤100 and y≂20 have been analyzed to yield hyperfine field distributions. The average hyperfine field is roughly proportional to the magnetization per iron atom and it can be fitted to the expression 〈Bhf〉 =aμFe +bμ̄ using the same coefficients (a=6 T/μB, b=9 T/μB) as for crystalline Fex Cr100−x. The region of onset of ferromagnetism around x=60 coincides with the inhomogeneous appearance of a moment on the iron, magnetic and nonmagnetic iron atoms coexisting at 4.2 K up to x=80. The variation in Curie temperature for 60≤x≤100 is mainly due to the variation of the iron moment. Chromium neighbors are much more effective in reducing the magnitude of the iron moment in glasses than in the bcc crystals, and some possible reasons for this are discussed.