Characterization of soft magnetic materials using a modified Stoner-Wohlfarth model

Abstract

In this paper a modification of the Stoner-Wohlfarth (SW) model is used to simulate the magnetic properties of soft materials. This modification has been used before in modelling the incoherent reversal processes in magnetic fine particles of the kind generally used in magnetic recording. In the case of particulate media the model gave good results, particularly in the prediction of the angular variation of the switching fields. In our model we consider that the magnetic properties of the soft magnetic materials can be obtained as a superposition of quasi-SW particles. These particles have different axial and transverse switching fields. The axial switching field corresponds to the low energy process of wall displacement with the domain walls crossing over the material imperfections, but the transverse one is a high field corresponding to the crystalline anisotropy field and to the reversible rotation of the particle moment. The example presented considers the case of aligned materials, with the magnetic field applied along the alignment direction. In the case of rotational hysteresis, torque curves were calculated for different values of the applied field strength.