TMR read head structures with differential stripe heights

1. A tunneling magnetoresistance (TMR) read head comprising:

a free layer having a free layer stripe height, the free layer having a first side and a second side;

a pinned stack disposed adjacent to the first side of the free layer, the pinned stack comprising at least one magnetic layer having a current path stripe height that is less than the free layer stripe height; and

a dielectric layer disposed adjacent to the at least one magnetic layer and above an area of the free layer not having the pinned stack disposed thereover.

2. The TMR read head of claim 1 , wherein the pinned stack comprises a reference layer, a pinned layer, and an antiferromagnetic layer.

3. The TMR read head of claim 2 , wherein, in the pinned stack, the at least one magnetic layer having the current path strip is the reference layer.

4. The TMR read head of claim 2 , wherein each of the reference, pinned and antiferromagnetic layers has a stripe height that is substantially equal to the current path stripe height.

5. The TMR read head of claim 4 further comprising a tunneling barrier layer disposed between the free layer and the pinned stack and having a stripe height substantially equal to the current path stripe height.

6. The TMR read head of claim 5 further comprising a first shield disposed below the free layer and a second shield disposed above the pinned stack, each of the first and second shields having a stripe height substantially equal to the free layer stripe height.

7. The TMR read head of claim 1 , wherein a ratio of the current path stripe height to the free layer stripe height is less than 0.5.

8. A tunneling magnetoresistance (TMR) read head comprising:

a free layer having a free layer stripe height, the free layer having a first side and a second side; and

a pinned stack disposed adjacent to the first side of the free layer, the pinned stack comprising at least one magnetic layer having a current path stripe height that is less than the free layer stripe height,

the pinned stack having a first surface disposed proximate to a magnetic recording medium and a second surface disposed opposite to the first surface at the current path stripe height from the first surface, wherein a magnetic flux emanating from the magnetic recording medium has a first magnetic flux value at the first surface and a second magnetic flux value at the second surface, further wherein a ratio of the second magnetic flux value to the first magnetic flux value is greater than 0.5.

9. The TMR read head of claim 8 further comprising a nonmagnetic insulating material disposed between the first and second shields and abutting the second surface of the pinned stack, the nonmagnetic insulating material extending from the current path stripe height to the free layer stripe height.

10. A hard disk drive comprising the TMR read head of claim 1 .

11. A method of producing a tunneling magnetoresistance (TMR) read head, the method comprising:

providing a free layer having a free layer stripe height, the free layer having a first side and a second side;

forming a tunneling barrier layer adjacent to the first side of the free layer, the tunneling barrier layer having a first side and a second side, the second side of the tunneling barrier layer facing the first side of the free layer;

forming a pinned stack adjacent to the first side of the tunneling barrier layer, the pinned stack comprising at least one magnetic layer having a current path stripe height that is less than the free layer stripe height; and

forming a dielectric layer adjacent to the at least one magnetic layer and above an area of the free layer not having the pinned stack disposed thereover.

12. The method of claim 11 , wherein a ratio of the current path stripe height to the free layer stripe height is less than 0.5.

13. The method of claim 11 , wherein the tunnel barrier layer has a stripe height substantially equal to the free layer stripe height.

14. The method of claim 11 , wherein the pinned stack comprises a reference layer, a pinned layer, and an antiferromagnetic layer.

15. The method of claim 14 , wherein at least the reference layer has the current path stripe height.

16. The method of claim 11 , wherein forming the pinned stack comprises forming an initial pinned stack having a stripe height substantially equal to the free layer stripe height.

17. The method of claim 16 , wherein removing a portion of the initial pinned stack to form the pinned stack having the current path stripe height.

18. The method of claim 16 further comprising forming a nonmagnetic insulating material adjacent to the pinned stack.

19. The method of claim 17 , wherein the nonmagnetic insulating material comprises aluminum oxide (Al 2 O 3 ).

20. The method of claim 17 further comprising forming a shield layer over the pinned stack and the nonmagnetic insulating material.