Magnetoresistive sensor having a high resistance soft magnetic layer between sensor stack and shield
View Patent ↗A magnetoresistive sensor has a high resistance soft magnetic layer disposed between the sensor stack and at least one magnetic shield. The presence of the high resistance soft magnetic layer allows a smaller magnetic read gap to be achieved which results in higher recording density. The susceptibility of the magnetoresistive sensor to defects and electrostatic damage is improved. A disk drive is provided having the novel magnetoresistive sensor.
1. A magnetoresistive sensor, comprising:
a magnetoresistive sensor stack responsive to an external magnetic field;
first and second magnetic shields, wherein said magnetoresistive sensor stack is disposed between said first and second magnetic shields;
a first insulating layer disposed between said magnetoresistive sensor stack and said first magnetic shield;
a second insulating layer disposed between said magnetoresistive sensor stack and said second magnetic shield;
a high resistance soft magnetic layer disposed between at least one of said insulating layers and one of said magnetic shields closest thereto;
wherein said high resistance soft magnetic layer has a magnetic moment greater than about 80 emu/cc,
wherein said high resistance soft magnetic layer has a composition of A-B-C where A is Co, B is selected from the group consisting of Hf, Y, Ta, and Zr, and C is N.
2. A magnetoresistive sensor as in claim 1 wherein a magnetic moment of each of the shields is less than the magnetic moment of the high resistance soft magnetic layer.
3. A magnetoresistive sensor as in claim 1 wherein said high resistance soft magnetic layer has a resistivity greater than 2000 micro-ohm-cm.
4. A magnetoresistive sensor as in claim 1 wherein said high resistance soft magnetic layer has a permeability greater than about 200.
5. A magnetoresistive sensor as in claim 1 wherein said high resistance soft magnetic layer has a thickness of about 0.07 microns to about 2 microns.
6. A magnetoresistive sensor as in claim 1 wherein at least one of said insulating layers comprises a material selected from the group consisting of alumina, silicon oxide, silicon nitride, and tantalum oxide.
7. A magnetoresistive sensor as in claim 1 wherein said high resistance soft magnetic layer has a magnetic moment that allows said high resistance soft magnetic layer to function as a magnetic shield without magnetically saturating.
8. A magnetoresistive sensor as in claim 1 wherein said high resistance soft magnetic layer has a coercivity of less than about 10 Oe.
9. A disk drive, comprising:
a magnetic disk;
a write head for writing information to said disk;
a magnetoresistive sensor for reading information from said disk, wherein said magnetoresistive sensor includes:
a magnetoresistive sensor stack responsive to an external magnetic field;
first and second magnetic shields wherein said magnetoresistive sensor stack is disposed between said first and second magnetic shields;
a first insulating layer disposed between said magnetoresistive sensor stack and said first magnetic shield;
a second insulating layer disposed between said magnetoresistive sensor stack and said second magnetic shield; and,
a high resistance soft magnetic layer disposed between at least one of said insulating layers and one of said magnetic shields closest thereto,
wherein said high resistance soft magnetic layer has a composition of A-B-C where A is Co, B is selected from the group consisting of Hf, Y, Ta, and Zr, and C is N.
10. A disk drive as in claim 9 wherein said high resistance soft magnetic layer has a magnetic moment greater than about 80 emu/cc.
11. A disk drive as in claim 9 wherein said high resistance soft magnetic layer has a resistivity greater than about 2000 micro-ohm-cm.
12. A disk drive as in claim 9 wherein a permeability of said high resistance soft magnetic layer is greater than about 200.
13. A disk drive as in claim 9 wherein said first and second insulating layers comprise a material selected from the group consisting of alumina, silicon oxide, silicon nitride, and tantalum oxide.