Hyperfine magnetic field distributions of Fe0.8-qMnqAl0.2 disordered alloys:: Interpretation in a local model

In order to give an interpretation of the room temperature hyperfine magnetic field distributions of Fe0.8-qMnqAl0.2 (0 less than or equal to q less than or equal to 0.25) disordered alloys, we employ a local model based on a binomial distribution method. In the model, the constituent atoms are assumed to be randomly distributed in a b.c.c. lattice accordingly with the disordered character of the system and its crystalline structure. Results show that the substitution of an iron atom by an aluminum atom, in the first Fe coordination shell, produces a reduction in the hyperfine field of 20.8 kOe. Analogously, the substitution Fe by Mn originates a reduction of 24.1 kOe. Differently from this, substitutions in the second coordination shell produce reductions of 6.6 kOe and 3.3 kOe for Al and Mn, respectively. The model allows also obtaining the average hyperfine field as well as to determine the most probable configurations (sites) of the system, involving nearest and next nearest neighbors. Finally, results are compared with experimental results obtained by Mossbauer spectroscopy.