Magnetic write head with write-field enhancement structure including a magnetic notch
A write head for a data storage device comprises a main pole, a trailing shield, and a write-field enhancement structure disposed in a write gap between the main pole and the trailing shield. The write-field enhancement structure comprises a non-magnetic spacer, a non-magnetic layer, and a magnetic DC-field-generation (DFG) layer. The DFG layer is sandwiched between the non-magnetic layer and the non-magnetic spacer. The write head also includes at least one magnetic notch adjacent to at least one of the main pole or the trailing shield. The non-magnetic spacer is adjacent to a magnetic notch. Some embodiments include multiple magnetic notches. Also disclosed are data storage devices comprising such write heads.
1. A data storage device, comprising:
at least one recording media;
a write head for writing to the at least one recording media, the write head comprising:
a main pole,
a trailing shield,
a magnetic notch adjacent to either the trailing shield or the main pole,
a non-magnetic spacer situated between the main pole and the trailing shield,
a non-magnetic layer situated between the main pole and the trailing shield, and
a magnetic DC-field-generation (DFG) layer adjacent to the non-magnetic spacer and situated between the non-magnetic spacer and the non-magnetic layer, wherein the magnetic DFG layer is the only magnetic layer between the main pole and the trailing shield that is not adjacent to the main pole or the trailing shield;
a first conducting line for providing a write current to the main pole;
a second conducting line for providing a bias current to the magnetic DFG layer; and
signal processing circuitry coupled to the first and second conducting lines and configured to control the write current and the bias current,
wherein a polarization and a spin diffusion length of the magnetic notch are selected such that, in operation, the magnetic notch provides spin-torque to align a DC component of a magnetization of the DFG layer in a direction that is substantially opposite to a gap field direction, and wherein the polarization exceeds a threshold polarization value and the spin diffusion length is less than a threshold spin diffusion length value.
2. The data storage device recited in claim 1 , wherein the magnetic notch is a first magnetic notch adjacent to the trailing shield, and further comprising a second magnetic notch adjacent to the main pole.
3. The data storage device recited in claim 1 , wherein:
a width of the magnetic notch is substantially identical to a width of the DFG layer, and
a height of the magnetic notch is substantially identical to a height of the DFG layer.
4. The data storage device recited in claim 1 , wherein at least one of a width of the magnetic notch or a height of the magnetic notch is less than about 50 nm.
5. The data storage device recited in claim 1 , wherein the magnetic notch comprises at least two layers.
6. The data storage device recited in claim 1 , wherein (a) the magnetic notch is adjacent to the trailing shield and is disposed between the trailing shield and the non-magnetic spacer, or (b) the magnetic notch is adjacent to the main pole and is disposed between the main pole and the non-magnetic spacer.
7. The data storage device recited in claim 6 , wherein the trailing shield and the magnetic notch are made of identical materials or the main pole and the magnetic notch are made of identical materials.
8. The data storage device recited in claim 1 , wherein a thickness of an effective write gap of the write head, the effective write gap including the non-magnetic spacer, the non-magnetic layer, the magnetic notch, and the magnetic DFG layer, is between approximately 15 nm and approximately 25 nm.
9. A data storage device, comprising:
at least one recording media;
a write head for writing to the at least one recording media, the write head comprising:
a main pole,
a trailing shield,
a magnetic notch adjacent to either the trailing shield or the main pole,
a non-magnetic spacer situated between the main pole and the trailing shield,
a non-magnetic layer situated between the main pole and the trailing shield, and
a magnetic DC-field-generation (DFG) layer adjacent to the non-magnetic spacer and situated between the non-magnetic spacer and the non-magnetic layer, wherein the magnetic DFG layer is the only magnetic layer between the main pole and the trailing shield that is not adjacent to the main pole or the trailing shield;
a first conducting line for providing a write current to the main pole;
a second conducting line for providing a bias current to the magnetic DFG layer; and
signal processing circuitry coupled to the first and second conducting lines and configured to control the write current and the bias current,
wherein a damping of the magnetic notch is selected such that, in operation, the magnetic notch provides spin-torque to align a DC component of a magnetization of the DFG layer in a direction that is substantially opposite to a gap field direction, and wherein the damping exceeds a threshold damping value.
10. The data storage device recited in claim 9 , wherein the magnetic notch is a first magnetic notch adjacent to the trailing shield, and further comprising a second magnetic notch adjacent to the main pole.
11. The data storage device recited in claim 9 , wherein:
a width of the magnetic notch is substantially identical to a width of the DFG layer, and
a height of the magnetic notch is substantially identical to a height of the DFG layer.
12. The data storage device recited in claim 9 , wherein at least one of a width of the magnetic notch or a height of the magnetic notch is less than about 50 nm.
13. The data storage device recited in claim 9 , wherein the magnetic notch comprises at least two layers.
14. The data storage device recited in claim 9 , wherein (a) the magnetic notch is adjacent to the trailing shield and is disposed between the trailing shield and the non-magnetic spacer, or (b) the magnetic notch is adjacent to the main pole and is disposed between the main pole and the non-magnetic spacer.
15. The data storage device recited in claim 14 , wherein the trailing shield and the magnetic notch are made of identical materials or the main pole and the magnetic notch are made of identical materials.
16. The data storage device recited in claim 9 , wherein a thickness of an effective write gap of the write head, the effective write gap including the non-magnetic spacer, the non-magnetic layer, the magnetic notch, and the magnetic DFG layer, is between approximately 15 nm and approximately 25 nm.
17. The data storage device recited in claim 9 , wherein (a) the magnetic notch is adjacent to the trailing shield and is disposed between the trailing shield and the non-magnetic spacer, or (b) the magnetic notch is adjacent to the main pole and is disposed between the main pole and the non-magnetic spacer.
18. The data storage device recited in claim 17 , wherein the trailing shield and the magnetic notch are made of identical materials or the main pole and the magnetic notch are made of identical materials.
19. A data storage device, comprising:
at least one recording media;
a write head for writing to the at least one recording media, the write head comprising:
a main pole,
a trailing shield,
a magnetic notch adjacent to either the trailing shield or the main pole,
a non-magnetic spacer situated between the main pole and the trailing shield,
a non-magnetic layer situated between the main pole and the trailing shield, and
a magnetic DC-field-generation (DFG) layer adjacent to the non-magnetic spacer and situated between the non-magnetic spacer and the non-magnetic layer, wherein the magnetic DFG layer is the only magnetic layer between the main pole and the trailing shield that is not adjacent to the main pole or the trailing shield;
a first conducting line for providing a write current to the main pole;
a second conducting line for providing a bias current to the magnetic DFG layer; and
signal processing circuitry coupled to the first and second conducting lines and configured to control the write current and the bias current,
wherein a resistivity of the magnetic notch is selected such that, in operation, the magnetic notch provides spin-torque to align a DC component of a magnetization of the DFG layer in a direction that is substantially opposite to a gap field direction, and wherein the resistivity is less than a threshold resistivity value.
20. The data storage device recited in claim 19 , wherein the magnetic notch is a first magnetic notch adjacent to the trailing shield, and further comprising a second magnetic notch adjacent to the main pole.
21. The data storage device recited in claim 19 , wherein:
a width of the magnetic notch is substantially identical to a width of the DFG layer, and
a height of the magnetic notch is substantially identical to a height of the DFG layer.
22. The data storage device recited in claim 19 , wherein at least one of a width of the magnetic notch or a height of the magnetic notch is less than about 50 nm.
23. The data storage device recited in claim 19 , wherein the magnetic notch comprises at least two layers.
24. The data storage device recited in claim 20 , wherein a thickness of an effective write gap of the write head, the effective write gap including the non-magnetic spacer, the non-magnetic layer, the magnetic notch, and the magnetic DFG layer, is between approximately 15 nm and approximately 25 nm.