Vector magnetization processes in amorphous magnetic materials with uniaxial induced anisotropy

We report an investigation about the vector magnetization behavior of soft amorphous materials. Disk-shaped samples, with uniaxial-induced anisotropy, were submitted to a magnetizing field Ha; oscillating along different directions with respect to the easy axis. The measured effective field H and the magnetization display a general behavior versus Ha; pointing out the crucial role played by the demagnetizing field. Experiments revealed two regimes in the magnetization reversal. This phenomenology was interpreted in the framework of the N!eel phase theory applied to uniaxial systems. We showed that the two experimental regimes correspond to magnetization modes where two or one magnetic phases (magnetic domains) are present. We worked out the switching condition between the modes, which involve only magnitude and orientation of the applied field. Moreover, in the two-phase mode, a simple relationship connecting the magnetization direction to the applied field direction was found. The measured magnetization properties are then interpreted as the combined action of domain wall motion without hysteresis and coherent rotation inside domains. It is remarkable that agreement found is based on two parameters only: the demagnetizing coefficient and the anisotropy field of the specimens.