Characterization of inductive recording heads by magnetic force microscopy

We report two developments in the emerging technique of recording head characterization by Magnetic Force Microscopy (MFM). The MFM signal amplitude was used to measure the field magnitude at the single pole tip of a vertical high-M_s FeAlN/NiFe write head as a function of input current. This method enabled us to observe directly the onset of saturation in a high-M_s write head. Scans over the pole tips of a longitudinal NiFe head, on the other hand, revealed features asymmetric across the gap and of identical sense upon current reversal. These features constitute possible evidence for magnetization rotation of the nominally “hard” Co-alloy MFM tip as a function of down-track position