Embodiments of the invention provide a countermeasure against spike noise
maintaining the data reliability of a magnetic recording layer. In one
embodiment, the magnetic domain state right below and around the read
head of the soft magnetic layer in the recording medium is locally and
temporarily equalized using the write head, whereby, the effect of the
spike noise caused by the magnetic domain boundaries (magnetic domain
walls) of the soft magnetic layer on the read waveform is prevented. The
read retry action of the magnetic hard disk drive is used as the trigger
for the timing of the magnetic field application, thereby shortening the
time for the magnetic field application.