Magnetic recording head and magnetic recording/reproducing apparatus

• US 8,537,497 B2
• Filed: 02/23/2012
• Issued: 09/17/2013
• Est. Priority Date: 08/29/2011
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Nagasaka, Keiichi, Shiimoto, Masato, Sato, Yo
• Primary Examiner(s): Klimowicz, Will J
• Application Number:
  US13/402,949
• Publication Number:
  US 20130050869A1
• Time in Patent Office: 572 Days
• Field of Search: 360/128, 360/125.3, 360/125.71
• US Class Current: 360/125.3
• CPC Class Codes: G11B 2005/0024 Microwave assisted recording
• CPC Class Codes: G11B 5/3146 magnetic layers
• CPC Class Codes: H01F 10/3272 by use of anti-parallel coupled [APC] ferromagnetic layers, e.g. artificial ferrimagnets [AFI], artificial [AAF] or synthetic [SAF] anti-ferromagnets
• CPC Class Codes: H01F 10/3286 Spin-exchange coupled multilayers having at least one layer with perpendicular magnetic anisotropy
• CPC Class Codes: H01F 10/329 Spin-exchange coupled multilayers wherein the magnetisation of the free layer is switched by a spin-polarised current, e.g. spin torque effect
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

In high frequency magnetic assisted recording technique, a spin torque oscillator that stably oscillates at a low current and a magnetic recording head with high recording density are provided. In a magnetic recording head including an oscillator that generates a high frequency magnetic field, a spin injection layer structure of two laminated magnetic layers which are coupled to be anti-parallel is adopted. A product Ms×t of the saturated magnetization Ms and the film thickness t of the first magnetic layer close to a field generation layer is smaller than a product Ms×t of the second magnetic layer remote from the field generation layer.

Claims

1. A magnetic head, comprising:

a magnetic main pole for generating a magnetic recording field; and

an oscillator provided adjacent to the magnetic main pole for generating a high frequency magnetic field, wherein

the oscillator includes a first spin injection layer structure and a field generation layer, and

when the first spin injection layer structure has a laminated layer structure in which a first magnetic layer, a coupling intermediate layer, and a second magnetic layer are laminated from a side close to the field generation layer, magnetization of the first magnetic layer and magnetization of the second magnetic layer are coupled to be anti-parallel, a product of saturated magnetization and a film thickness of the first magnetic layer is indicated as Ms×

t_SIL11, and a product of saturated magnetization and a film thickness of the second magnetic layer is indicated as Ms×

t_SIL12, the following relationship satisfied;

Ms×

t_SIL11<

Ms×

t_SIL12.

2. The magnetic head according to claim 1, wherein, when an anisotropy field of the first magnetic layer is indicated as Hk_SIL11 and an anisotropy field of the second magnetic layer is indicated as Hk_SIL12, the following relationship is satisfied:

Hk_SIL11>

Hk_SIL12.

3. The magnetic head according to claim 1, wherein a current is applied from the field generation layer to the first spin injection layer structure.

4. The magnetic head according to claim 2, wherein a current is applied from the field generation layer to the first spin injection layer structure.

5. The magnetic head according to claim 1, wherein a magnetization direction of the first spin injection layer structure is switched by a magnetic leakage field from the magnetic main pole.

6. The magnetic head according to claim 2, wherein a magnetization direction of the first spin injection layer structure is switched by a magnetic leakage field from the magnetic main pole.

7. The magnetic head according to claim 1, wherein a second spin injection layer structure is provided opposite to the first spin injection layer structure over the field generation layer.

8. The magnetic head according to claim 2, wherein a second spin injection layer structure is provided opposite to the first spin injection layer structure over the field generation layer.

9. The magnetic head according to claim 7, wherein the second spin injection layer structure is a single layer structure or a multilayer structure including a plurality of magnetic layers in which magnetization is in the same direction.

10. The magnetic head according to claim 8, wherein the second spin injection layer structure is a single layer structure or a multilayer structure including a plurality of magnetic layers in which magnetization is in the same direction.

11. The magnetic head according to claim 9, wherein magnetization of the second spin injection layer structure and magnetization of the first magnetic layer in the first spin injection layer structure are in opposite directions.

12. The magnetic head according to claim 10, wherein magnetization of the second spin injection layer structure and magnetization of the first magnetic layer in the first spin injection layer structure are in opposite directions.

13. The magnetic head according to claim 7, wherein a current is applied from the second spin injection layer structure to the first spin injection layer structure.

14. The magnetic head according to claim 8, wherein a current is applied from the second spin injection layer structure to the first spin injection layer structure.

15. The magnetic head according to claim 7, wherein a magnetization direction of the first spin injection layer structure and a magnetization direction of the second spin injection layer structure are switched by a magnetic leakage field from the magnetic main pole.

16. The magnetic head according to claim 8, wherein a magnetization direction of the first spin injection layer structure and a magnetization direction of the second spin injection layer structure are switched by a magnetic leakage field from the magnetic main pole.

17. The magnetic head according to claim 1, comprising:

a magnetic reproducing head.

18. The magnetic head according to claim 2, comprising:

a magnetic reproducing head.

19. A magnetic recording/reproducing device, comprising:

a magnetic recording medium;

a medium driving unit for driving the magnetic recording medium;

a magnetic head for recording and reproducing information on the magnetic recording medium; and

a head driving unit for positioning the magnetic head on a desired track of the magnetic recording medium, wherein

the magnetic head according to claim 17 is used as the magnetic head.

20. A magnetic recording/reproducing device, comprising:

a magnetic recording medium;

a medium driving unit for driving the magnetic recording medium;

a magnetic head for recording and reproducing information on the magnetic recording medium; and

a head driving unit for positioning the magnetic head on a desired track of the magnetic recording medium, wherein

the magnetic head according to claim 18 is used as the magnetic head.