Magnetic head to prevent undesired data erasure and magnetic disk storage having the same

1. A magnetic head comprising:

a write head having a main pole and an auxiliary pole; and

a read head having a lower reader shield, an upper reader shield, and a read element located between said lower reader shield and said upper reader shield;

wherein b>a and b≧c are satisfied where, on an air-bearing surface, a denotes a cross-track width of said auxiliary pole, b denotes a cross-track width of said upper reader shield, and c denotes a cross-track width of said lower reader shield,

wherein d 1 ≦t 1 and d 2 ≦t 2 are satisfied where d 1 denotes a positional difference between edges of said auxiliary pole and upper reader shield on the air-bearing surface in the cross-track direction, d 2 denotes a positional difference between edges of said upper reader shield and lower reader shield on the air-bearing surface in the cross-track direction, t 1 denotes the film thickness of said auxiliary pole or upper reader shield, whichever of magnetic layers constituting said auxiliary pole and said upper reader is larger in cross-track width, and t 2 denotes the film thickness of said upper reader shield or lower reader shield, whichever is larger in cross-track width.

2. The magnetic head as claimed in claim 1 , wherein b>c is satisfied.

3. The magnetic head as claimed in claim 1 , wherein regarding a magnetic layer constituting said auxiliary pole, a magnetic layer constituting said lower reader shield, and a magnetic layer constituting said upper reader shield, a positional difference between edges of two neighboring magnetic layers thereof is smaller than the film thickness of whichever of the two neighboring magnetic layers is larger in cross-track width.

4. The magnetic head as claimed in claim 3 , wherein d 1 and d 2 are not more than about 1μm.

5. The magnetic head as claimed in claim 3 , wherein a magnetic layer magnetically connected with said auxiliary pole on the air-bearing surface is provided and d 3 , a positional difference between edges of said auxiliary pole and said magnetic layer on the air-bearing surface in the cross-track direction is smaller than the film thickness of said auxiliary pole or said magnetic layer, whichever is larger in cross-track width.

6. The magnetic head as claimed in claim 1 , wherein a trailing side shield having a magnetic layer is provided on the trailing side of the main pole in the cross-track direction and a positional difference between edges of said auxiliary pole and said magnetic layer on the air-bearing surface in the cross-track direction is smaller than the film thickness of said auxiliary pole or said magnetic layer, whichever is larger in cross-track length.

7. The magnetic head as claimed in claim 1 , wherein |l−m|≦t 5 and |m−n|≦ t 6 are satisfied, where l, m and n respectively denote the lengths of said auxiliary pole, said upper reader shield and said lower reader shield in the element height direction, and t 5 denotes the film thickness of said auxiliary pole or said upper reader shield, whichever is longer in the element height direction and t 6 denotes the film thickness of said upper reader shield or said lower reader shield, whichever is longer in the element height direction.

8. The magnetic head as claimed in claim 1 , wherein |l−m| ≦t 5 and |m−n|≦t 6 are satisfied, where l, m and n respectively denote the lengths of said auxiliary pole, said upper reader shield and said lower reader shield in the element height direction, and t 5 denotes the film thickness of said auxiliary pole or said upper reader shield, whichever is longer in the element height direction and t 6 denotes the film thickness of said upper reader shield or said lower reader shield, whichever is longer in the element height direction.

9. A magnetic disk storage comprising:

a magnetic recording medium having a magnetic recording layer and a soft under layer;

a medium drive which drives said magnetic recording medium;

a magnetic head which writes to, and reads from, said magnetic recording medium; and

a magnetic head drive which drives said magnetic head with respect to said magnetic reading medium:

wherein said magnetic head comprising:

a write head having a main pole and an auxiliary pole; and

a read head having a lower reader shield, an upper reader shield, and a read element located between said lower reader shield and said upper reader shield;

wherein b>a and b≧c are satisfied where, on an air-bearing surface, a denotes a cross-track width of said auxiliary pole, b denotes a cross-track width of said upper reader shield, and c denotes a cross-track width of said lower reader shield,

wherein d 1 ≦t 1 and d 2 ≦t 2 are satisfied where d 1 denotes a positional difference between edges of said auxiliary pole and upper reader shield on the air-bearing surface in the cross-track direction, d 2 denotes a positional difference between edges of said upper reader shield and lower reader shield on the air-bearing surface in the cross-track direction, t 1 denotes the film thickness of said auxiliary pole or upper reader shield, whichever of magnetic layers constituting said auxiliary pole and said upper reader is larger in cross-track width, and t 2 denotes the film thickness of said upper reader shield or lower reader shield, whichever is larger in cross-track width.

10. A magnetic disk storage comprising:

a magnetic recording medium having a magnetic recording layer and a soft under layer;

a medium drive which drives said magnetic recording medium;

a magnetic head which writes to, and reads from, said magnetic recording medium; and

a magnetic head drive which drives said magnetic head with respect to said magnetic reading medium;

wherein said magnetic head comprising:

a write head having a main pole and an auxiliary pole; and

a read head having a lower reader shield, an upper reader shield, and a read element located between said lower reader shield and said upper reader shield;

wherein b>a and b≧c are satisfied where, on an air-bearing surface, a denotes a cross-track width of said auxiliary pole, b denotes a cross-track width of said upper reader shield, and c denotes a cross-track width of said lower reader shield,

wherein d 1 ≦t 1 and d 2 ≦t 2 are satisfied where d 1 denotes a positional difference between edges of said auxiliary pole and upper reader shield on the air-bearing surface in the cross-track direction, d 2 denotes a positional difference between edges of said upper reader shield and lower reader shield on the air-bearing surface in the cross-track direction, t 1 denotes the film thickness of said auxiliary pole or upper reader shield, whichever of magnetic layers constituting said auxiliary pole and said upper reader is larger in cross-track width, and t 2 denotes the film thickness of said upper reader shield or lower reader shield, whichever is larger in cross-track width.

11. A method of manufacturing a magnetic head, said method comprising:

providing a magnetic head comprising:

a write head having a main pole and an auxiliary pole; and

a read head having a lower reader shield, an upper reader shield, and a read element located between said lower reader shield and said upper reader shield;

wherein b>a and b≧c are satisfied where, on an air-bearing surface, a denotes a cross-track width of said auxiliary pole, b denotes a cross-track width of said upper reader shield, and c denotes a cross-track width of said lower reader shield,

wherein d 1 ≦t 1 and d 2 ≦t 2 are satisfied where d 1 denotes a positional difference between edges of said auxiliary pole and upper reader shield on the air-bearing surface in the cross-track direction, d 2 denotes a positional difference between edges of said upper reader shield and lower reader shield on the air-bearing surface in the cross-track direction, t 1 denotes the film thickness of said auxiliary pole or upper reader shield, whichever of magnetic layers constituting said auxiliary pole and said upper reader is larger in cross-track width, and t 2 denotes the film thickness of said upper reader shield or lower reader shield, whichever is larger in cross-track width,

making a magnetic layer for said upper reader shield;

making an inorganic insulating layer above and on the sides of said magnetic layer; and

planarizing said magnetic layer and said inorganic insulating layer.

12. The magnetic head manufacturing method as claimed in claim 11 , wherein said planarizing is carried out by chemical mechanical polishing.

13. A method of manufacturing a magnetic head, said method comprising:

providing a magnetic head comprising:

a write head having a main pole and an auxiliary pole; and

a read head having a lower reader shield, an upper reader shield, and a read element located between said lower reader shield and said upper reader shield;

wherein b>a and b≧c are satisfied where, on an air-bearing surface, a denotes a cross-track width of said auxiliary pole, b denotes a cross-track width of said upper reader shield, and c denotes a cross-track width of said lower reader shield,

wherein d 1 ≦t 1 and d 2 ≦t 2 are satisfied where d 1 denotes a positional difference between edges of said auxiliary pole and upper reader shield on the air-bearing surface in the cross-track direction, d 2 denotes a positional difference between edges of said upper reader shield and lower reader shield on the air-bearing surface in the cross-track direction, t 1 denotes the film thickness of said auxiliary pole or upper reader shield, whichever of magnetic layers constituting said auxiliary pole and said upper reader is larger in cross-track width, and t 2 denotes the film thickness of said upper reader shield or lower reader shield, whichever is larger in cross-track width,

making a gap layer on the lower reader shield with the read element between them;

making a resist frame for plating;

plating a magnetic layer for the upper reader shield;

plating a non-magnetic layer;

plating a magnetic layer for the auxiliary pole; and removing the resist frame.