Interpretation based on a binomial method of the hyperfine field distributions of disordered Fe0.9-xMn0.1Alx alloys

In order to give an interpretation of the room temperature hyperfine magnet ic field distributions of disordered Fe0.9-xMn0.1Alx (0.1 less than or equa l to x less than or equal to 0.5) alloys, we employ a local model based on a binomial distribution method. In the model, the constituent atoms are ass umed to be randomly distributed in a BCC lattice accordingly with the disor dered character of the system and its crystalline structure. Results show t hat the substitution of an iron atom by an aluminum atom, in the first Fe c oordination shell, produces a reduction in the hyperfine field of 20.8 kOe. Analogously, the substitution of Fe by Mn produces a reduction of 24.1 kOe . Differently from this, substitutions in the second coordination shell pro duce reductions of 6.6 and 3.3 kOe for Al and Mn, respectively. The model a lso allows to obtain the average hyperfine field as well as to determine th e most probable configurations (sites) of the system, involving nearest and next nearest neighbors. Finally, results are compared with experimental re sults obtained by Mossbauer spectroscopy. (C) 2000 Elsevier Science B.V. Al l rights reserved.