A technique for de-gaussing the pole tips and yoke of a write transducer
in a perpendicular magnetic recording system is provided. An oscillator
in the read channel is configured to produce an adjustable signal pattern
output to the preamplifier when a write operation ends for a given time
and at a predetermined frequency, such that as the preamplifier write
current decays, it decays with transitions (polarity reversals). This
results in a decaying AC field being applied to the write transducer at
the end of a media write operation, effectively de-gaussing it and
reducing the effects of remanent magnetization remaining in the poles and
yoke of the magnetic recording head after a write current is turned off.
This defeats a potential pole tip lockup or yoke lockup circumstance in
the magnetic recording media which can result in an inability to write
further data or a possible erasure of valid data on the hard disk with
which the write head is associated.