Hysteresis loop asymmetry induced by magnetic annealing in Fe-Al alloy

It is experimentally shown, by means of convenient magnetic annealing treatments, that the hysteresis loop of an Fe-Al alloy can be modified in a strongly asymmetric way. A zero differential permeability can be obtained along magnetic field intervals at any given point of the loop. This phenomenon, besides producing ferromagnetic materials having very peculiar characteristics, provides fundamental information about the effects of mutual interactions among Bloch walls during their movement towards a given configuration, stabilized by annealing. Moreover, the experimental results show that stabilization of a given wall configuration, performed under pressure exerted by an external magnetic field, has unidirectional features, limiting more effectively wall movements in the same direction as the pressure applied during the heat treatment. This proves that potential energy wells of asymmetric shape can be created within the alloy by means of convenient annealing techniques.