Quantitative magneto-optic field imaging of recording heads (abstract)

With increasingly higher recording densities and narrowing track widths approaching 1 micron in particular it is getting more important to optimize the field distribution of the write head. The goal is to minimize side writing due to fringing fields at the pole edges as well as distortions of the write field contour along the track width emanating from gap saturation. The imaging of written transitions in a recording medium using a magnetic force microscope yields information only about the integral response of the head/medium magnetic system. We have developed a technique to measure the magnetic field distribution at the gap quantitatively using a transducer layer deposited directly on the air bearing surface. Other than an in-plane magnetized medium with hysteretic behavior the perpendicularly oriented Co/Pt multilayer shows reversible nonhysteretic rotation of magnetization when subjected to the in-plane component of the recording head. Consequently, a quantitative determination of the write field is p...