Write transducer having a magnetic buffer layer spaced between a side shield and a write pole by non-magnetic layers
View Patent ↗A write transducer for a disk drive magnetic head includes a ferromagnetic write yoke having a write pole protruding towards an air bearing surface. The write transducer also includes a ferromagnetic side shield, and a ferromagnetic buffer layer disposed between the write yoke and the side shield. A first non-magnetic layer is disposed between the side shield and the ferromagnetic buffer layer. A second non-magnetic layer is disposed between the ferromagnetic buffer layer and the write yoke. The ferromagnetic buffer layer extends in a direction normal to the air bearing surface by a buffer layer throat height in the range of 10 nm to 500 nm. In certain embodiments, such a write transducer may advantageously reduce undesired wide area track erasure, without unacceptably degrading write field rise time for acceptable on-track writing data rate.
1. A write transducer comprising:
a write yoke comprising a first ferromagnetic material and including a write pole protruding from the write yoke towards an air bearing surface of the write transducer;
a side shield comprising a second ferromagnetic material;
a ferromagnetic buffer layer disposed between the write yoke and the side shield, the ferromagnetic buffer layer comprising a third ferromagnetic material;
a first non-magnetic layer disposed between the side shield and the ferromagnetic buffer layer, the ferromagnetic buffer layer being spaced from the side shield by no less than a thickness of the first non-magnetic layer; and
a second non-magnetic layer disposed between the ferromagnetic buffer layer and the write yoke, the ferromagnetic buffer layer being spaced from the write yoke by no less than a thickness of the second non-magnetic layer;
wherein the ferromagnetic buffer layer extends in a direction normal to the air bearing surface by a buffer layer throat height in the range of 10 nm to 500 nm, and wherein the third ferromagnetic material has a magnetic moment that is 0.6 to two times that of the second ferromagnetic material.
2. The write transducer of claim 1 wherein the write pole protrudes from the write yoke along a write pole axis that is normal to the air bearing surface.
3. The write transducer of claim 1 wherein the thickness of the first non-magnetic layer is in the range of 10 nm to 300 nm, as measured in a direction normal to the air bearing surface.
4. The write transducer of claim 1 wherein the thickness of the second non-magnetic layer is in the range of 100 nm to 1 μm, as measured in a direction normal to the air bearing surface.
5. The write transducer of claim 1 wherein the side shield spans a side shield throat height in the range of 50 nm to 600 nm, as measured in a direction normal to the air bearing surface.
6. The write transducer of claim 1 wherein the write transducer is a perpendicular magnetic recording write transducer, and the first ferromagnetic material has a composition Co 30 Fe 70 .
7. The write transducer of claim 1 wherein the second ferromagnetic material has a composition selected from the group consisting of Ni 30 Fe 70 , Co 69 Ni 14 Fe 17 , and Co 50 Ni 15 Fe 35 .
8. The write transducer of claim 1 wherein the third ferromagnetic material has the same composition as the second ferromagnetic material.
9. The write transducer of claim 1 wherein the third ferromagnetic material has a magnetic moment of no less than 1.6 Tesla.
10. The write transducer of claim 1 wherein each of the first and second non-magnetic layers comprises aluminum oxide, titanium oxide, or magnesium oxide.
11. The write transducer of claim 1 wherein the write pole includes a pole tip disposed adjacent to the air bearing surface, the pole tip being separated from the side shield by a side gap, the side gap comprising a non-magnetic metal layer having a thickness in the range of 10 nm to 100 nm.
12. The write transducer of claim 11 wherein the pole tip has a triangular cross sectional shape in a plane parallel to the air bearing surface, and the non-magnetic metal layer comprises ruthenium, tantalum, or copper.
13. The write transducer of claim 1 further comprising a ferromagnetic wrap-around shield structure that comprises the side shield and the second ferromagnetic material, the ferromagnetic wrap-around shield structure surrounding the write pole in a plane parallel to the air bearing surface.
14. The write transducer of claim 1 wherein the ferromagnetic buffer layer is one of a plurality of ferromagnetic buffer layers disposed between the write yoke and the side shield, each separated from another by a non-magnetic decoupling layer having a thickness in the range of 10 nm to 300 nm, as measured in a direction normal to the air bearing surface.
15. A magnetic head comprising:
a slider having an air bearing surface and a trailing face approximately orthogonal to the air bearing surface;
a write transducer disposed on the trailing face, the write transducer comprising
a write yoke comprising a first ferromagnetic material and including a write pole protruding from the write yoke towards the air bearing surface;
a side shield comprising a second ferromagnetic material;
a ferromagnetic buffer layer disposed between the write yoke and the side shield, the ferromagnetic buffer layer comprising a third ferromagnetic material;
a first non-magnetic layer disposed between the side shield and the ferromagnetic buffer layer, the ferromagnetic buffer layer being spaced from the side shield by no less than a thickness of the first non-magnetic layer; and
a second non-magnetic layer disposed between the ferromagnetic buffer layer and the write yoke, the ferromagnetic buffer layer being spaced from the write yoke by no less than a thickness of the second non-magnetic layer;
wherein the ferromagnetic buffer layer extends in a direction normal to the air bearing surface by a buffer layer throat height in the range of 10 nm to 500 nm, and wherein the third ferromagnetic material has a magnetic moment that is 0.6 to two times that of the second ferromagnetic material.
16. The magnetic head of claim 15 wherein the thickness of the first non-magnetic layer is in the range of 10 nm to 300 nm, as measured in a direction normal to the air bearing surface.
17. The magnetic head of claim 15 wherein the thickness of the second non-magnetic layer is in the range of 100 nm to 1 μm, as measured in a direction normal to the air bearing surface.
18. The magnetic head of claim 15 wherein the side shield spans a side shield throat height in the range of 50 nm to 600 nm, as measured in a direction normal to the air bearing surface.
19. The magnetic head of claim 15 wherein the third ferromagnetic material has the same composition as the second ferromagnetic material.
20. The magnetic head of claim 15 wherein the third ferromagnetic material has a magnetic moment of no less than 1.6 Tesla.
21. The magnetic head of claim 15 wherein the write pole includes a pole tip disposed adjacent to the air bearing surface, the pole tip being separated from the side shield by a side gap, the side gap comprising a non-magnetic metal layer having a thickness in the range of 10 nm to 100 nm.
22. The magnetic head of claim 15 further comprising a ferromagnetic wrap-around shield structure that comprises the side shield and the second ferromagnetic material, the ferromagnetic wrap-around shield structure surrounding the write pole in a plane parallel to the air bearing surface.
23. The magnetic head of claim 15 wherein the ferromagnetic buffer layer is one of a plurality of ferromagnetic buffer layers disposed between the write yoke and the side shield, each separated from another by a non-magnetic decoupling layer having a thickness in the range of 10 nm to 300 nm, as measured in a direction normal to the air bearing surface.
24. A disk drive comprising:
a disk drive base;
a spindle attached to the disk drive base and defining a spindle axis of rotation;
a disk rotatably mounted on the spindle;
a head actuator attached to the disk drive base;
a magnetic head attached to the head actuator; the magnetic head comprising
a slider having an air bearing surface facing the disk, and a trailing face approximately orthogonal to the air bearing surface;
a write transducer disposed on the trailing face, the write transducer comprising
a write yoke comprising a first ferromagnetic material and including a write pole protruding from the write yoke towards the air bearing surface;
a side shield comprising a second ferromagnetic material;
a ferromagnetic buffer layer disposed between the write yoke and the side shield, the ferromagnetic buffer layer comprising a third ferromagnetic material;
a first non-magnetic layer disposed between the side shield and the ferromagnetic buffer layer, the ferromagnetic buffer layer being spaced from the side shield by no less than a thickness of the first non-magnetic layer; and
a second non-magnetic layer disposed between the ferromagnetic buffer layer and the write yoke, the ferromagnetic buffer layer being spaced from the write yoke by no less than a thickness of the second non-magnetic layer;
wherein the ferromagnetic buffer layer extends in a direction normal to the air bearing surface by a buffer layer throat height in the range of 10 nm to 500 nm, and wherein the third ferromagnetic material has a magnetic moment that is 0.6 to two times that of the second ferromagnetic material.