EFFECT OF ATOMIC ENVIRONMENT ON THE FE-57 HYPERFINE FIELD IN FE2MNSI

Fe2MnSi forms the Heusler-type L2(1) structure with some degree of preferential DO3 disorder, in which about 10% of the Mn sites (c sites) are occupied by iron atoms. The observed Mossbauer spectrum of Fe2MnSi at 5.5 K is considered to be composed of four kinds of sextets. This spectrum can be well explained by a model based on the effect of atomic environment. The hyperfine field of Fe-57 atoms on the Fe sites (b, and d sites) is considered to vary with the number of neighboring iron atoms n. They are 64, 116, and 158 kOe for n = 0, 1, and 2, respectively. The field of the Fe-57 on the c-sites with about eight neighboring iron atoms is 287 kOe. It may be concluded that the iron atoms without their neighboring iron atoms have a very small, or nearly zero, magnetic moment, from the empirical relation between magnetic moment and magnetic hyperfine field.