Temperature and field behavior of magnetic properties of ordered alloys Fe100?xAlx (25 < x < 35 at %)

Results of M?ssbauer and magnetic studies of partially ordered alloys Fe_{100 − x} Al _x (25 < x < 35 at %) are discussed depending on the temperature and applied magnetic field. Two variants of the interpretation of the temperature behavior of magnetization and average hyperfine magnetic field at ⁵⁷Fe nuclei in the model of a collinear magnet with magnetic inhomogeneities of a nanometer range are suggested. In the first variant, the existence of clusters with magnetic moments oriented parallel and antiparallel to the total magnetization is assumed. Temperature anomalies, such as the nonmonotonic dependence of magnetization and hyperfine magnetic field in the temperature range of 100–200 K, are explained at a qualitative level by the stabilization of relaxation phenomena in clusters due to Stoner-type spin excitations. The second variant is based on the assumption of a change in the orientation of spins antiparallel to the magnetization with increasing temperature.