There is disclosed a disk drive having a magnetic device for applying a
direct current magnetic field to the disk 1 by using a disk with a
double-layered structure in which a soft magnetic layer is provided on a
lower layer of the recording magnetic layer. The magnetic device generates
a direct current magnetic field to uniform a magnetic domain state of the
soft magnetic layer of the disk. The intensity of the direct current is
larger than the anisotropic magnetic field of the soft magnetic layer and
is smaller than the coercive force of the recording magnetic layer. As a
consequence, the stabilization of the magnetic domain state of the soft
magnetic layer of the disk can be realized to make an attempt of
decreasing the magnetic noise and establishing stabilization with respect
to the disturbance magnetic field.
