Hyperfine fields and magnetic moments of crystalline Co3−xFexB and glassy Co4−xFexB alloys

A Mössbauer and NMR study of crystalline orthorhombic Co3−xFexB has been undertaken. Two different 57Fe hyperfine fields, varying only slightly with x, corresponding to two types of Fe surroundings in the Co3B structure have been found. Fe moments in the range 2.15–2.23 and 1.73–1.87μB have been estimated. Transferred hyperfine field (THF) at 11B has a strong local character depending on the chemical and topological short-range order around B. Contributions to THF (B) from Fe belonging to the first six neighbors and to the next three neighbors have been separated and evaluated. An analysis of THF (B) for Co4−xFexB amorphous alloys has shown that in the glassy form the short-range order is similar to that in crystalline Co3−xFexB only in the case of Co4B.