Magnetic hyperfine temperature dependence in Fe-Si crystalline alloys

Fe-Si crystalline alloys with different silicon contents (4.5, 12, 18 and 2 6 at.%) were investigated by Fe-57 Mossbauer spectrometry and a.c. magnetic measurements in order to get magnetic hyperfine data as a function of temp erature and Curie temperatures as a function of silicon content at the diff erent iron sites. The values of critical exponent beta which are independen t on the iron site are found close to 0.36, typical of Heisenberg ferromagn ets, whatever the silicon content. The present results support the assumpti ons made in the literature to describe the magnetic and hyperfine propertie s of FINEMET nanocrystalline alloys and can further be considered. (C) 1999 Elsevier Science Ltd. All rights reserved.