Kerr imaging of a thin film magnetic transducer to measure thin film head fields

In this work, the field generated by a magnetic recording head is measured by sensing the magnetization of a transducer film, placed in proximity to the ABS of the head. The magnetization is measured by sensing Kerr rotation of a 250 nm laser spot scanned over the transducer at a step size of 55 nm. Since this measurement provides transducer normal magnetization, rather than normal field, the associated head fields are computed by iteratively solving the torque balance on the transducer magnetization and Laplace´s equation. This yields a vector field consistent with the observed transducer magnetization and the transducer magnetization gradients. Using this technique the fringing fields of a head with a 0.33 μm gap and a 2 μm trackwidth are measured