Inductive writer design using a soft magnetic pedestal having a high magnetic saturation layer
View Patent ↗A magnetic head for writing information on a relatively-moving medium includes a first substantially flat soft magnetic pole layer and a second substantially flat pole layer with at least one coil layer between them. The pole layers are magnetically coupled in a core region and spaced by more than one micron from one other. A soft magnetic pedestal adjoins the first pole layer adjacent to a medium-facing surface of the head, and a first high magnetic saturation layer adjoins the pedestal. A second high magnetic saturation layer adjoins the second pole layer. The first high magnetic saturation layer has a first throat height and the second high magnetic saturation layer extends from the medium-facing surface only to a second throat height. The first and second throat heights are within about one and one-half microns from the medium-facing surface and are essentially equal.
1. A magnetic head for writing information on a relatively-moving medium, the head having a leading end, a trailing end and a medium-facing surface, the head comprising:
a first substantially flat soft magnetic pole layer disposed in the head adjacent to the medium-facing surface and extending substantially perpendicular to the medium-facing surface;
a second substantially flat soft magnetic pole layer disposed in the head adjacent to the medium-facing surface and oriented substantially parallel to the first soft magnetic layer, the second pole layer spaced greater than one micron from the first pole layer and magnetically coupled to the first pole layer in a core region removed from the medium-facing surface;
a soft magnetic pedestal that adjoins the first substantially flat soft magnetic pole layer adjacent to the medium-facing surface;
a first high magnetic saturation layer that adjoins the soft magnetic pedestal;
a second high magnetic saturation layer that adjoins the second substantially flat soft magnetic pole layer and is separated from the first high magnetic saturation layer by a nanoscale nonferromagnetic gap, the first high magnetic saturation layer having a first throat height and the second high magnetic saturation layer extending from the medium-facing surface only to a second throat height, wherein the first and second throat heights are within about one and one-half microns from the medium-facing surface and are essentially equal; and
at least one coil layer disposed between the first substantially flat soft magnetic pole layer and the second substantially flat soft magnetic pole layer.
2. The magnetic head of claim 1 , further comprising a magnetoresistive sensor.
3. The magnetic head of claim 2 , wherein the magnetoresistive sensor is separated from the first substantially flat soft magnetic pole layer by a soft magnetic shield layer.
4. The magnetic head of claim 2 , wherein the magnetoresistive sensor is disposed between the second substantially flat soft magnetic pole layer and a soft magnetic shield layer.
5. The magnetic head of claim 4 , wherein the magnetoresistive sensor is within one-quarter micron of the second substantially flat soft magnetic pole layer.
6. The magnetic head of claim 1 , wherein the first substantially flat soft magnetic pole layer adjoins a substrate extending a distance from the first substantially flat soft magnetic pole layer to the leading end greater than a distance between the first substantially flat soft magnetic pole layer and the trailing end.
7. The magnetic head of claim 1 , wherein the first high magnetic saturation layer comprises a first portion extending from the medium-facing surface only to the first throat height and a second portion extending beyond the first throat height.
8. The magnetic head of claim 7 , wherein the first portion of the first high magnetic saturation layer is formed by trimming the first high magnetic saturation layer at the first throat height to produce first and second portions that have identical track-width dimensions and are aligned in the track-width direction.
9. The magnetic head of claim 7 , wherein the first portion of the first high magnetic saturation layer is thicker than the second portion.
10. The magnetic head of claim 7 , wherein the first portion of the first high magnetic saturation layer has a first thickness of at least fifty nanometers and less than one half of a micron and the second portion has a second thickness at least twenty nanometers and less than one fourth of a micron.
11. The magnetic head of claim 10 , wherein the second section is substantially flat with a substantially constant spacing from the second substantially flat soft magnetic layer.
12. The magnetic head of claim 1 , wherein a track-width dimension of the first high magnetic saturation layer is less than one-quarter micron.
13. The magnetic head of claim 1 , wherein a track-width dimension of the first high magnetic saturation layer is less than 100 nanometers.
14. The magnetic head of claim 1 , wherein the soft magnetic pedestal has a track-width dimension identical to the first high magnetic saturation layer.
15. The magnetic head of claim 1 , wherein the second substantially flat soft magnetic pole layer has a flare point beyond the second throat height.
16. The magnetic head of claim 1 , wherein the first high magnetic saturation layer and the second high magnetic saturation layer each have a magnetic saturation of at least twenty kiloGauss.