High-resolution magnetooptic imaging of the high-frequency magnetic behavior of ferrite recording heads

The magnetic response in the vicinity of the gap of a ferrite recording head has been imaged magnetooptically at frequencies of up to 50 MHz with a spatial resolution of under 0.5 μm. The measurements show that different grains in the ferrite provide different amplitude and phase of response, presumably as a result of their different crystalline orientations. Magnetic activity across grain boundaries is evident, indicating small magnetic discontinuities between grains. The results graphically demonstrate the potential for magnetic nonuniformities in polycrystalline ferrites, and they show that heads using such ferrites may exhibit less than desirable behavior for track widths nearly as narrow as the grains