Inductance and Read-Write Characteristics for Thin Film Heads

The inductance and read-write characteristics for thin film heads with various magnetostriction constants were investigated. Heads consisting of a top yoke with positive magnetostriction constants and a bottom yoke with negative constants, exhibited excellent read-write characteristics. Such a result can be explained by an increase in the difference between the inductance at zero bias, and that when the core pieces are magnetized, that is, by the permeability of the core pieces. High permeability was caused by the magnetoelastic effect based on the induced uniaxial stresses in permalloy films. In addition, the overwrite level improved dramatically as certain values of the bias magnetomotive force, determined from the inductance characteristics, increased. It was concluded that the measurement of the inductance characteristics is a very powerful method for evaluating the performance of pole tips and taped regions of thin film heads.