Low Bs spin-polarizer for spin torque oscillator

• US 9,230,569 B1
• Filed: 11/26/2014
• Issued: 01/05/2016
• Est. Priority Date: 11/26/2014
• Status: Active Grant

• Current Assignee: JP Morgan Chase Bank, N.A. (JP Morgan Chase & Co)
• Original Assignee: HGST Netherlands B.V. (Western Digital Corporation)
• Inventors: Shimoto, Masato, Igarashi, Masukazu, Nagasaka, Keiichi, Sato, Yo, Okamura, Susumu, Sato, Masashige
• Primary Examiner(s): Cao, Allen T
• Application Number:
  US14/555,484
• Time in Patent Office: 405 Days
• Field of Search: 360/125.3, 360/125.31, 360/125.03, 360/125.09, 360/125.04, 360/125.17, 360/125.12, 360/125.16, 360/125.14
• US Class Current: 1/1
• CPC Class Codes: G11B 2005/0024 Microwave assisted recording
• CPC Class Codes: G11B 5/147 with cores being composed of metal sheets, i.e. laminated cores with cores composed of isolated magnetic layers, e.g. sheets in thin films G11B5/31
• CPC Class Codes: G11B 5/314 where the layers are extra layers normally not provided in the transducing structure, e.g. optical layers G11B5/3196 takes precedence

Abstract

In one embodiment, a magnetic head includes a main magnetic pole positioned configured to generate a writing magnetic field when current is applied to a write coil, and a spin torque oscillator (STO) located adjacent the main magnetic pole, the STO being configured to generate a high frequency magnetic field when current is applied thereto, wherein the high frequency magnetic field is generated simultaneously to the writing magnetic field to assist in reversing magnetization of a magnetic recording medium. The STO includes: a spin polarization layer (SPL), a field generation layer (FGL) positioned adjacent the SPL, and one or more interlayers positioned between the SPL and the FGL, and a magnetization easy axis of the SPL is positioned in an in-plane direction such that the SPL has no perpendicular magnetic anisotropy.

Claims

1. A magnetic head, comprising:

a main magnetic pole configured to generate a writing magnetic field when current is applied to a write coil; and

a spin torque oscillator (STO) located adjacent the main magnetic pole, the STO being configured to generate a high frequency magnetic field when current is applied thereto, wherein the high frequency magnetic field is generated simultaneously to the writing magnetic field,

wherein the STO comprises;

a spin polarization layer (SPL);

a field generation layer (FGL) positioned adjacent the SPL; and

one or more interlayers positioned between the SPL and the FGL, and

wherein a magnetization easy axis of the SPL is positioned in an in-plane direction such that the SPL has no perpendicular magnetic anisotropy.

2. The magnetic head as recited in claim 1, further comprising a trailing shield positioned on a SPL-side of the STO, the trailing shield being configured to act as a return electrode, wherein the STO is positioned at a media-facing surface adjacent to the main magnetic pole between the main magnetic pole and the trailing shield.

3. The magnetic head as recited in claim 1, further comprising a trailing shield positioned on a FGL-side of the STO, the trailing shield being configured to act as a return electrode, wherein the STO is positioned at a media-facing surface adjacent to the main magnetic pole between the main magnetic pole and the trailing shield.

4. The magnetic head as recited in claim 1, wherein a saturation magnetic flux density of the SPL (Bs_SPL) multiplied by a thickness of the SPL (t_SPL) is less than a saturation magnetic flux density of the FGL (Bs_FGL) multiplied by a thickness of the FGL (t_FGL).

5. The magnetic head as recited in claim 1, wherein the SPL comprises at least one of Ni, Fe, and Co, and wherein a product of a saturation magnetic flux density of the SPL (Bs_SPL) and a thickness of the SPL (t_SPL) is no greater than about 10 nmT.

6. The magnetic head as recited in claim 5, wherein the SPL further comprises a nonmagnetic material (X) selected from a group consisting of:

Cu, Ge, Si, and B, and wherein Bs_SPL*t_SPL≦

5 nmT.

7. The magnetic head as recited in claim 6, wherein when the SPL comprises NiX, the nonmagnetic material constitutes from about 0.1 at % to about 50 at % of the NiX.

8. The magnetic head as recited in claim 6, wherein when the SPL comprises CoFeX, the nonmagnetic material constitutes from about 20 at % to about 80 at % of the CoFeX.

9. The magnetic head as recited in claim 1, wherein a thickness of the SPL is in a range from about 0.5 nm to about 10 nm.

10. The magnetic head as recited in claim 1, wherein current is flowed through the STO in a direction from the FGL to the SPL.

11. A magnetic data storage system, comprising:

at least one magnetic head as recited in claim 1;

a magnetic recording medium;

a drive mechanism for passing the magnetic recording medium over the at least one magnetic head; and

a controller electrically coupled to the at least one magnetic head for controlling operation of the at least one magnetic head.

12. A method for producing a magnetic head, the method comprising:

forming a main magnetic pole at a media-facing surface;

forming a spin torque oscillator (STO) above the main magnetic pole, the STO comprising;

a field generation layer (FGL) formed above the main magnetic pole;

a spin polarization layer (SPL) formed above the FGL; and

one or more interlayers formed between the SPL and the FGL,

wherein a magnetization easy axis of the SPL is positioned in an in-plane direction such that the SPL has no perpendicular magnetic anisotropy, and

wherein a saturation magnetic flux density of the SPL (Bs_SPL) multiplied by a thickness of the SPL (t_SPL) is less than a saturation magnetic flux density of the FGL (Bs_FGL) multiplied by a thickness of the FGL (t_FGL), such that Bs_SPL*t_SPL<

Bs_FGL*t_FGL.

13. The method as recited in claim 12, further comprising forming a trailing shield above the SPL, the trailing shield being configured to act as a return electrode.

14. The method as recited in claim 12, wherein the SPL comprises at least one of Ni, Fe, and Co, and wherein Bs_SPL*t_SPL≦

10 nmT.

15. The method as recited in claim 14, wherein the SPL further comprises a nonmagnetic material (X) selected from a group consisting of:

Cu, Ge, Si, and B, and wherein Bs_SPL*t_SPL≦

5 nmT.

16. The method as recited in claim 15, wherein when the SPL comprises NiX, the nonmagnetic material constitutes from about 0.1 at % to about 50 at % of the NiX.

17. The method as recited in claim 15, wherein when the SPL comprises CoFeX, the nonmagnetic material constitutes from about 20 at % to about 80 at % of the CoFeX.

18. A spin torque oscillator (STO), comprising:

a spin polarization layer (SPL);

a field generation layer (FGL) positioned adjacent the SPL; and

one or more interlayers positioned between the SPL and the FGL,

wherein a magnetization easy axis of the SPL is positioned in an in-plane direction such that the SPL has no perpendicular magnetic anisotropy, and wherein a saturation magnetic flux density of the SPL (Bs_SPL) multiplied by a thickness of the SPL (t_SPL) is less than a saturation magnetic flux density of the FGL (Bs_FGL) multiplied by a thickness of the FGL (t_FGL).

19. The STO as recited in claim 18, wherein the SPL comprises at least one of Ni, Fe, and Co, and wherein Bs_SPL*t_SPL≦

10 nmT.

20. The STO as recited in claim 19, wherein the SPL further comprises a nonmagnetic material (X) selected from a group consisting of:

Cu, Ge, Si, and B, and wherein Bs_SPL*t_SPL≦

5 nmT, wherein when the SPL comprises NiX, the nonmagnetic material constitutes from about 0.1 at % to about 50 at % of the NiX, and wherein when the SPL comprises CoFeX, the nonmagnetic material constitutes from about 20 at % to about 80 at % of the CoFeX.