System, method and apparatus for shape-engineered islands of exchange spring or exchange coupled composite, bit patterned media

A magnetic media disk, comprising:

• a substrate having an axis;
• an exchange coupled composite, bit patterned media on the substrate arranged in a plurality of tracks, each of the tracks having a pattern of islands extending in an axial direction from the substrate, and each island comprising:
• a first layer having a first anisotropy and a first layer radial width;
• a coupling layer on the first layer;
• and
• a second layer on the coupling layer having a second anisotropy that is lower than the first anisotropy, and a second layer radial width that is less than the first layer radial width.

A hard disk drive, comprising:

• an enclosure;
• a magnetic media disk mounted and rotatable about an axis relative to the enclosure, the magnetic media disk having an exchange coupled, bit patterned media arranged in a plurality of tracks, each of the tracks having a pattern of islands extending in an axial direction from the disk, and each island comprising:
• a first layer having a first layer radial width and a second layer on the first layer having a second layer radial width that is less than the first layer radial width;
• an actuator mounted to the enclosure and movable relative to the magnetic media disk, the actuator having a head with a head field contour for recording data to the tracks of the magnetic media disk;
• and
• the head field contour has a field width that extends to adjacent tracks, and the field width only extends to the first layer radial widths of the first layers of the islands on the adjacent tracks and not to the second layer radial widths.