Overwrite in thin film disk recording systems

Overwrite in thin film rigid disk recording is studied experimentally using disks with a wide range of magnetic moment and coercivity. Standard f₂/f₁ overwrite is investigated in detail at various recording currents and different flying heights. A theoretical model is developed using simple analytical approximations that relate demagnetization-field-induced position shift (hard transition shift) to the measured overwrite. The demagnetization fields due to the leading edge transitions are calculated analytically including a good approximation to the gapped head image. The results compare well with experimental measurements. A new overwrite measurement technique using the second harmonic component of a 0.5f₁, signal is also described