By forming a step in a lower core layer, the distance between the upper surface
of a Gd-defining layer and the lower core layer is changed stepwise. Consequently,
the distance between an upper magnetic pole layer formed on the upper surface of
the Gd-defining layer and the lower core layer is small in the front region of
the lower core layer, and thus a leakage magnetic field from the upper magnetic
pole layer is absorbed by the lower core layer and is not applied to a recording medium.
