Correlation of magnetic Barkhausen noise with core loss in oriented 3% Si-Fe steel laminates

The angular dependence of surface magnetic Barkhausen noise (MBN) with flux densities up to 1.7 T on eight different samples of oriented 3% Si-Fe steel laminate was investigated. On two of the samples encircled MBN measurements were performed. MBN energy values were obtained by integrating the square of the MBN voltage signal with respect to time. the angular variation of the MBN energy signal was modeled by considering anisotropic internal fields that moderate 180 degrees domain wall motion and the local eddy current field interactions between spatially correlated Barkhausen events. The eddy current field interactions arising between 180 degrees domain walls that lie along the sample's primary easy axis direction were represented by a parameter alpha alpha' had a cos theta angular dependence where theta is the angle of the applied sweep field with respect to the sample rolling direction. the angular averaged MBN energy signal, (Energy), was evaluated and compared with core losses measured using the standard Epstein technique at 1.5 T Surface MBN measurements on samples with higher (Energy) demonstrated lower core loss. This was associated with a larger proportion of microscopic eddy currents generated parallel to the sample lane which were, therefore, uncoupled from macroscopic eddy currents generated by the bulk magnetization of the sample. Larger surface (Energy) signals were identified with a finer domain wall structure. For samples with a nonzero alpha', the core loss was observed to decrease with increasing alpha' magnitude. This was interpreted as a result of a reduction of microscopic eddy currents arising from an increase in interactions between simultaneously moving 180 degrees domain walls. (C) 1996 American Institute of Physics.