Interaction effects in longitudinally oriented and non-oriented barium hexaferrite tapes

The observed magnetic interactions in barium hexaferrite tapes as a function of dispersion milling time and orientation are reported. Measurement of the interaction state is obtained by comparing the magnetizing and demagnetizing remanence curves. Variation in the interactions as a function of dispersion milling time in longitudinally oriented and nonoriented tapes indicates substantial changes in the interaction state of the constituent magnetic particles. In particular, the oriented tape samples exhibit an increasing net magnetizing interaction effect, whereas the nonoriented samples show a decreasing net magnetizing effect. These two markedly different effects are explained in terms of the improved dispersion and separation of barium hexaferrite platelets, which reduces the interaction parameter in the case of nonoriented tapes. In the longitudinally oriented form, however, the increased freedom of movement (associated with improved dispersion) results in the enhanced formation of stacking and particle columns