A method for manufacturing a magnetic core module in a magnetic head, the magnetic core module and the magnetic head. The method for manufacturing the magnetic core module includes: a process for placing a magnetic core group in a holder mold cavity as an insert; and a process for injection-molding in the holder mold cavity. A method for manufacturing the magnetic core module allows the magnetic core group and the holder to be integrally injection-molded with a method of injection molding which uses the magnetic core group as an insert. The method simplifies the process of manufacturing a magnetic head to improve production efficiency, and saves labor and production costs. Further, the method prevents failures such as positional displacement and scattering of magnetic cores, which tends to occur when assembling thin and small magnetic cores, and ensures an ideal yield for a product.

A dual PMR writer is disclosed wherein a first main pole (MP1) in writer 1 is a mirror image of a second main pole (MP2) in writer 2 with respect to a center plane aligned orthogonal to the air bearing surface (ABS). MP1 and MP2 may have an asymmetrical top-down shape to reduce writer-writer spacing (WWS) and read write offset (RWO) when a single or double reader is positioned down-track at the center plane. Accordingly, there is less track misregistration and better area density capability. Each of MP1 and MP2 as well as a top yoke (TY), and a tapered bottom yoke (tBY) have a rectangular back portion of width w from 4 to 10 microns. Spacing between MP1 and MP2 back portions may be 4 microns to prevent cross-talk. RWO is reduced from 4 microns for symmetrical TY/MP/tBY shapes to 3 microns or less for asymmetrical shapes.

A dual PMR writer is disclosed wherein a first main pole (MP1) in writer 1 is a mirror image of a second main pole (MP2) in writer 2 with respect to a center plane aligned orthogonal to the air bearing surface (ABS). MP1 and MP2 may have an asymmetrical top-down shape to reduce writer-writer spacing (WWS) and read write offset (RWO) when a single or double reader is positioned down-track at the center plane. Accordingly, there is less track misregistration and better area density capability. Each of MP1 and MP2 as well as a top yoke (TY), and a tapered bottom yoke (tBY) have a rectangular back portion of width w from 4 to 10 microns. Spacing between MP1 and MP2 back portions may be 4 microns to prevent cross-talk. RWO is reduced from 4 microns for symmetrical TY/MP/tBY shapes to 3 microns or less for asymmetrical shapes.

A magnetic write apparatus has a media-facing surface (MFS) and includes an auxiliary pole, coil(s) and a main pole having a pole tip and a yoke. The pole tip occupies part of the MFS. The yoke has a yoke length measured from the MFS in a yoke direction perpendicular to the MFS. The yoke length is less than four microns. The main pole has a total length in the yoke direction and a width in a cross-track direction. The main pole is continuous along the total length. The aspect ratio of the main pole is the total length divided by the width and exceeds one. The main pole includes surface(s) having a nonzero acute flare angle from the MFS. The auxiliary pole is adjacent to the main pole and recessed from the MFS by not more than 1.05 micron. The coil(s) energizes the main pole and have not more than two turns.

A method for manufacturing a magnetic core module in a magnetic head, the magnetic core module and the magnetic head. The method for manufacturing the magnetic core module includes: a process for placing a magnetic core group in a holder mold cavity as an insert; and a process for injection-molding in the holder mold cavity. A method for manufacturing the magnetic core module allows the magnetic core group and the holder to be integrally injection-molded with a method of injection molding which uses the magnetic core group as an insert. The method simplifies the process of manufacturing a magnetic head to improve production efficiency, and saves labor and production costs. Further, the method prevents failures such as positional displacement and scattering of magnetic cores, which tends to occur when assembling thin and small magnetic cores, and ensures an ideal yield for a product.

A reader having a bearing surface, a free layer, and a free layer biasing structure. The free layer biasing structure includes at least one side shield that applies a first bias field level to a front portion of the free layer that is nearest to the bearing surface and applies a second bias field level to a rear portion of the free layer that is farthest from the bearing surface. The second bias field level is greater than the first bias field level.

A method for manufacturing a magnetic core module in a magnetic head, the magnetic core module and the magnetic head. The method for manufacturing the magnetic core module includes: a process for placing a magnetic core group in a holder mold cavity as an insert; and a process for injection-molding in the holder mold cavity. A method for manufacturing the magnetic core module allows the magnetic core group and the holder to be integrally injection-molded with a method of injection molding which uses the magnetic core group as an insert. The method simplifies the process of manufacturing a magnetic head to improve production efficiency, and saves labor and production costs. Further, the method prevents failures such as positional displacement and scattering of magnetic cores, which tends to occur when assembling thin and small magnetic cores, and ensures an ideal yield for a product.

A magnetic write apparatus has a media-facing surface (MFS) and includes an auxiliary pole, coil(s) and a main pole having a pole tip and a yoke. The pole tip occupies part of the MFS. The yoke has a yoke length measured from the MFS in a yoke direction perpendicular to the MFS. The yoke length is less than four microns. The main pole has a total length in the yoke direction and a width in a cross-track direction. The main pole is continuous along the total length. The aspect ratio of the main pole is the total length divided by the width and exceeds one. The main pole includes surface(s) having a nonzero acute flare angle from the MFS. The auxiliary pole is adjacent to the main pole and recessed from the MFS by not more than 1.05 micron. The coil(s) energizes the main pole and have not more than two turns.

A magnetic write apparatus has a media-facing surface (MFS) and includes an auxiliary pole, coil(s) and a main pole having a pole tip and a yoke. The pole tip occupies part of the MFS. The yoke has a yoke length measured from the MFS in a yoke direction perpendicular to the MFS. The yoke length is less than four microns. The main pole has a total length in the yoke direction and a width in a cross-track direction. The main pole is continuous along the total length. The aspect ratio of the main pole is the total length divided by the width and exceeds one. The main pole includes surface(s) having a nonzero acute flare angle from the MFS. The auxiliary pole is adjacent to the main pole and recessed from the MFS by not more than 1.05 micron. The coil(s) energizes the main pole and have not more than two turns.

A reader having a bearing surface, a free layer, and a free layer biasing structure. The free layer biasing structure includes at least one side shield that applies a first bias field level to a front portion of the free layer that is nearest to the bearing surface and applies a second bias field level to a rear portion of the free layer that is farthest from the bearing surface. The second bias field level is greater than the first bias field level.