Method and apparatus for providing a free layer having higher saturation field capability and optimum sensitivity

1. A synthetic free layer for a magnetic read sensor, comprising:

a first free layer,

a composite coupling layer disposed over the first free layer, wherein the composite coupling layer comprises a first NiFe layer, an interlayer and a second NiFe layer; and

a second free layer disposed over the coupling layer, the second free layer comprising a cobalt alloy including at least one of nickel, niobium, molybdenum, tungsten, silicon and boron.

2. The synthetic free layer of claim 1 , wherein the interlayer comprises ruthenium.

3. The synthetic free layer of claim 1 , wherein the first free layer comprises CoFe.

4. The synthetic free layer of claim 1 , wherein the cobalt alloy including at least one of nickel, niobium, molybdenum, tungsten, silicon and boron prevents saturation without degrading magnetoresistive sensitivity.

5. The synthetic free layer of claim 1 , wherein the cobalt alloy including at least one of nickel, niobium, molybdenum, tungsten, silicon and boron provides higher magnetic anisotropy to avoid saturation.

6. A synthetic free layer for a magnetic read sensor, comprising:

a first free layer,

a coupling layer disposed over the first free layer, wherein the coupling layer comprises a first NiFe layer, an interlayer and a second NiFe layer; and

a second free layer disposed over the coupling layer, the second free layer comprising a cobalt alloy including at least one of molybdenum, tungsten, silicon and boron.

7. The synthetic free layer of claim 6 , wherein the interlayer comprises ruthenium.

8. The synthetic free layer of claim 6 , wherein the first free layer comprises CoFe.

9. The synthetic free layer of claim 6 , wherein the cobalt alloy including at least one of, molybdenum, tungsten, silicon and boron prevents saturation without degrading magnetoresistive sensitivity.

10. The synthetic free layer of claim 6 , wherein the cobalt alloy including at least one of, molybdenum, tungsten, silicon and boron provides higher magnetic anisotropy to avoid saturation.

11. A method for forming a synthetic free layer for a magnetic read sensor, comprising:

forming a first free layer,

forming a composite coupling layer over the first free layer, wherein the composite coupling layer comprises a first NiFe layer, an interlayer and a second NiFe layer; and

forming a second free layer over the coupling layer, the second free layer comprising a cobalt alloy including at least one of nickel, niobium, molybdenum, tungsten, silicon and boron.

12. A method for forming a synthetic free layer for a magnetic read sensor, comprising:

forming a first free layer,

forming a coupling layer over the first free layer, wherein the forming the coupling layer comprises forming a first NiFe layer, an interlayer and a second NiFe layer; and

forming a second free layer over the coupling layer, the second free layer comprising a cobalt alloy including at least one of molybdenum, tungsten, silicon and boron.

13. A magnetic read sensor, comprising:

a ferromagnetic fixed layer having a magnetization direction pinned in a particular direction;

a synthetic free layer having a magnetization that is free to rotate; and

a non-magnetic spacer layer disposed between the ferromagnetic pinned layer and the synthetic free layer;

wherein the synthetic free layer comprises:

a first free layer,

a composite coupling layer disposed over the first free layer, wherein the composite coupling layer comprises a first NiFe layer, an interlayer and a second NiFe layer; and

a second free layer disposed over the coupling layer, the second free layer comprising a cobalt alloy including at least one of nickel, niobium, molybdenum, tungsten, silicon and boron.

14. The synthetic free layer of claim 13 , wherein the interlayer comprises ruthenium.

15. The synthetic free layer of claim 13 , wherein the first free layer comprises CoFe.

16. The synthetic free layer of claim 13 , wherein the cobalt alloy including at least one of nickel, niobium, molybdenum, tungsten, silicon and boron prevents saturation without degrading magnetoresistive sensitivity.

17. The synthetic free layer of claim 13 , wherein the cobalt alloy including at least one of nickel, niobium, molybdenum, tungsten, silicon and boron provides higher magnetic anisotropy to avoid saturation.

18. A magnetic read sensor, comprising:

a ferromagnetic fixed layer having a magnetization direction pinned in a particular direction;

a synthetic free layer having a magnetization that is free to rotate; and

a non-magnetic spacer layer disposed between the ferromagnetic pinned layer and the synthetic free layer;

wherein the synthetic free layer comprises:

a first free layer,

a coupling layer disposed over the first free layer, wherein the coupling layer comprises a first NiFe layer, an interlayer and a second NiFe layer; and

a second free layer disposed over the coupling layer, the second free layer comprising a cobalt alloy including at least one of molybdenum, tungsten, silicon and boron.

19. The synthetic free layer of claim 18 , wherein the interlayer comprises ruthenium.

20. The synthetic free layer of claim 18 , wherein the first free layer comprises CoFe.

21. The synthetic free layer of claim 18 , wherein the cobalt alloy including at least one of, molybdenum, tungsten, silicon and boron prevents saturation without degrading magnetoresistive sensitivity.

22. The synthetic free layer of claim 18 , wherein the cobalt alloy including at least one of, molybdenum, tungsten, silicon and boron provides higher magnetic anisotropy to avoid saturation.

23. A magnetic storage device, comprising:

a magnetic media for storing data thereon;

a motor, coupled to the magnetic media, for translating the magnetic media;

a transducer for reading and writing data on the magnetic media; and

an actuator, coupled to the transducer, for moving the transducer relative to the magnetic media;

wherein the transducer includes a read sensor having a synthetic free layer, the synthetic free layer comprising a first free layer, a composite coupling layer disposed over the first free layer and a second free layer disposed over the coupling layer, the second free layer comprising a cobalt alloy including at least one of nickel, niobium, molybdenum, tungsten, silicon and boron and wherein the composite coupling layer comprises a first NiFe layer, an interlayer and a second NiFe layer.

24. A magnetic storage device, comprising:

a magnetic media for storing data thereon;

a motor, coupled to the magnetic media, for translating the magnetic media;

a transducer for reading and writing data on the magnetic media; and

an actuator, coupled to the transducer, for moving the transducer relative to the magnetic media;

wherein the transducer includes a read sensor having a synthetic free layer, the synthetic free layer comprising a first free layer, a coupling layer disposed over the first free layer and a second free layer disposed over the coupling layer, the second free layer comprising a cobalt alloy including at least one of molybdenum, tungsten, silicon and boron and wherein the coupling layer comprises a first NiFe layer, an interlayer and a second NiFe layer.

25. A synthetic free layer for a magnetic read sensor, comprising:

first means for providing a first magnetization that is free to rotate;

coupling means disposed over the first means for providing a first and second soft magnetic layer, wherein the coupling means comprises a first NiFe layer, an interlayer and a second NiFe layer; and

second means, disposed over the coupling means, for providing a second magnetization that is free to rotate, the second means comprising a cobalt alloy including at least one of nickel, niobium, molybdenum, tungsten, silicon and boron.

26. A synthetic free layer for a magnetic read sensor, comprising:

first means for providing a first magnetization that is free to rotate;

coupling means disposed over the first means, wherein the coupling layer comprises a first NiFe means, an interlayer and a second NiFe layer; and

second means, disposed over the coupling means, for providing a second magnetization that is free to rotate, the second means comprising a cobalt alloy including at least one of molybdenum, tungsten, silicon and boron.