THIN-FILM MAGNETIC HEAD FOR MICROWAVE ASSIST AND MICROWAVE-ASSISTED MAGNETIC RECORDING METHOD

• US 20090310244A1
• Filed: 06/17/2008
• Published: 12/17/2009
• Est. Priority Date: 06/17/2008
• Status: Abandoned Application

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Chou, Tsutomu, Tsuchiya, Yoshihiro, Shimazawa, Koji
• Application Number:
  US12/140,670
• Publication Number:
  US 20090310244A1
• Time in Patent Office: Days
• US Class Current: 360/75
• CPC Class Codes: G11B 2005/0024 Microwave assisted recording
• 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

Provided is a thin-film magnetic head that can stably generate electromagnetic field with a desired frequency, even under the existence of significantly strong write field with frequently reversed direction. The head comprises an electromagnetic-field generating element between the first and second magnetic poles. The electromagnetic-field generating element comprises a spin-wave excitation layer provided adjacent to the first magnetic pole and having a magnetization with its direction varied according to external magnetic fields, for generating an high frequency electromagnetic field by an excitation of spin wave. And a magnetization of the spin-wave excitation layer is biased in a direction substantially perpendicular to its layer surface by a portion of magnetic field generated from the first magnetic pole, and pin-wave excitation current flows in the electromagnetic-field generating element in a direction from the second pole to the first pole.

Claims

1. A thin-film magnetic head comprising:

a first magnetic pole for generating a write field for writing to a magnetic recording medium, and a second magnetic pole; and

an electromagnetic-field generating element provided in a position reaching an opposed-to-medium surface, between said first magnetic pole and said second magnetic pole,

said electromagnetic-field generating element comprising;

a spin-wave excitation layer provided adjacent to said first magnetic pole and having a magnetization with its direction varied according to external magnetic fields, for generating an high frequency electromagnetic field by an excitation of spin wave; and

a non-magnetic intermediate layer provided on a side opposite to said first magnetic pole in relation to said spin-wave excitation layer, and

a magnetization of said spin-wave excitation layer being biased in a direction substantially perpendicular to its layer surface by a portion of magnetic field generated from said first magnetic pole, and an electric current for exciting the spin wave flowing in said electromagnetic-field generating element in a direction from said second magnetic pole to said first magnetic pole.

2. The thin-film magnetic head as claimed in claim 1, wherein said spin-wave excitation layer has a magnetic anisotropy energy of 1×

10⁴ erg/cm³ or less.

3. The thin-film magnetic head as claimed in claim 1, wherein said spin-wave excitation layer has an axis of easy magnetization perpendicular to its layer surface.

4. The thin-film magnetic head as claimed in claim 1, wherein:

said spin-wave excitation layer further comprises a magnetization free layer having a magnetization with its direction varied according to external magnetic fields;

said non-magnetic intermediate layer is provided in a position sandwiched between said magnetization free layer and said spin-wave excitation layer; and

a magnetization of said magnetization free layer is biased in a direction substantially perpendicular to its layer surface by a portion of magnetic field generated from said first magnetic pole.

5. The thin-film magnetic head as claimed in claim 4, wherein said magnetization free layer has a magnetic anisotropy energy of 1×

10⁴ erg/cm³ or less.

6. The thin-film magnetic head as claimed in claim 4, wherein said magnetization free layer has an axis of easy magnetization perpendicular to its layer surface.

7. The thin-film magnetic head as claimed in claim 1, wherein said second magnetic pole comprises a protruding portion that is provided on an end portion on the opposed-to-medium surface side of said second magnetic pole, opposed to said first magnetic pole, and protrudes toward said first magnetic pole, and said electromagnetic-field generating element is provided between said protruding portion and said first magnetic pole.

8. The thin-film magnetic head as claimed in claim 1, wherein said first magnetic pole comprises a protruding portion that is provided on an end portion on the opposed-to-medium surface side of said first magnetic pole, opposed to said second magnetic pole, and protrudes toward said second magnetic pole, and said electromagnetic-field generating element is provided between said protruding portion and said second magnetic pole.

9. The thin-film magnetic head as claimed in claim 1, wherein a portion of said first magnetic pole or said second magnetic pole is formed of an electrically insulating layer, and an end portion on the opposed-to-medium surface side of said first magnetic pole and an end portion on the opposed-to-medium surface side of said second magnetic pole act as electrodes for applying the electric current for exciting the spin wave to said electromagnetic-field generating element.

10. The thin-film magnetic head as claimed in claim 1, wherein a width in a track width direction of an end on the opposed-to-medium surface side of said electromagnetic-field generating element is smaller than a width in a track width direction of an end on the opposed-to-medium surface side of said first magnetic pole.

11. The thin-film magnetic head as claimed in claim 1, wherein a frequency of the high frequency electromagnetic field generated from said spin-wave excitation layer is substantially equal to a magnetic resonance frequency of a magnetic recording layer of the magnetic recording medium to be written.

12. A head gimbal assembly comprising:

the thin-film magnetic head as claimed in claim 1; and

a support structure for supporting said thin-film magnetic head.

13. A magnetic recording apparatus comprising:

at least one head gimbal assembly comprising a thin-film magnetic head and a suspension for supporting said thin-film magnetic head;

at least one magnetic recording medium; and

a recording circuit for controlling write operation of said thin-film magnetic head performed to said at least one magnetic recording medium,

said thin-film magnetic head comprising;

a first magnetic pole for generating a write field for writing to the magnetic recording medium, and a second magnetic pole; and

an electromagnetic-field generating element provided in a position reaching an opposed-to-medium surface, between said first magnetic pole and said second magnetic pole,

said electromagnetic-field generating element comprising;

a spin-wave excitation layer provided adjacent to said first magnetic pole and having a magnetization with its direction varied according to external magnetic fields, for generating an high frequency electromagnetic field by an excitation of spin wave; and

a non-magnetic intermediate layer provided on a side opposite to said first magnetic pole in relation to said spin-wave excitation layer,

a magnetization of said spin-wave excitation layer being biased in a direction substantially perpendicular to its layer surface by a portion of magnetic field generated from said first magnetic pole, and an electric current for exciting the spin wave flowing in said electromagnetic-field generating element in a direction from said second magnetic pole to said first magnetic pole, and

said recording circuit further comprising a spin-wave control circuit for controlling the electric current for exciting the spin wave.

14. The magnetic recording apparatus as claimed in claim 13, wherein said spin-wave excitation layer has a magnetic anisotropy energy of 1×

10⁴ erg/cm³ or less.

15. The magnetic recording apparatus as claimed in claim 13, wherein said spin-wave excitation layer has an axis of easy magnetization perpendicular to its layer surface.

16. The magnetic recording apparatus as claimed in claim 13, wherein:

said spin-wave excitation layer further comprises a magnetization free layer having a magnetization with its direction varied according to external magnetic fields;

said non-magnetic intermediate layer is provided in a position sandwiched between said magnetization free layer and said spin-wave excitation layer; and

a magnetization of said magnetization free layer is biased in a direction substantially perpendicular to its layer surface by a portion of magnetic field generated from said first magnetic pole.

17. The magnetic recording apparatus as claimed in claim 16, wherein said magnetization free layer has a magnetic anisotropy energy of 1×

10⁴ erg/cm³ or less.

18. The magnetic recording apparatus as claimed in claim 16, wherein said magnetization free layer has an axis of easy magnetization perpendicular to its layer surface.

19. The magnetic recording apparatus as claimed in claim 13, wherein said second magnetic pole comprises a protruding portion that is provided on an end portion on the opposed-to-medium surface side of said second magnetic pole, opposed to said first magnetic pole, and protrudes toward said first magnetic pole, and said electromagnetic-field generating element is provided between said protruding portion and said first magnetic pole.

20. The magnetic recording apparatus as claimed in claim 13, wherein said first magnetic pole comprises a protruding portion that is provided on an end portion on the opposed-to-medium surface side of said first magnetic pole, opposed to said second magnetic pole, and protrudes toward said second magnetic pole, and said electromagnetic-field generating element is provided between said protruding portion and said second magnetic pole.

21. The magnetic recording apparatus as claimed in claim 13, wherein a portion of said first magnetic pole or said second magnetic pole is formed of an electrically insulating layer, and an end portion on the opposed-to-medium surface side of said first magnetic pole and an end portion on the opposed-to-medium surface side of said second magnetic pole act as electrodes for applying the electric current for exciting the spin wave to said electromagnetic-field generating element.

22. The magnetic recording apparatus as claimed in claim 13, wherein a width in a track width direction of an end on the opposed-to-medium surface side of said electromagnetic-field generating element is smaller than a width in a track width direction of an end on the opposed-to-medium surface side of said first magnetic pole.

23. The magnetic recording apparatus as claimed in claim 13, wherein a frequency of the high frequency electromagnetic field generated from said spin-wave excitation layer is substantially equal to a magnetic resonance frequency of a magnetic recording layer of the magnetic recording medium to be written.

24. A magnetic recording method comprising steps of:

biasing a magnetization of a spin-wave excitation layer including a layer surface perpendicular to an opposed-to-medium surface and having the magnetization with its direction varied according to external magnetic fields, in a direction substantially perpendicular to the layer surface, by a portion of magnetic field generated from a magnetic pole;

exciting a spin wave in said spin-wave excitation layer by applying an electric current to said spin-wave excitation layer with its magnetization biased;

reducing an anisotropic magnetic field of a portion of a magnetic recording medium, by applying a high frequency magnetic field generated by the spin wave to the portion of the magnetic recording medium, the high frequency magnetic field including an in-plane component in a direction within the magnetic recording medium; and

performing writing on the portion with the reduced anisotropic magnetic field of the magnetic recording medium, by applying a write field generated from said magnetic pole.

25. The magnetic recording method as claimed in claim 24, wherein a magnetic anisotropy energy of said spin-wave excitation layer is set to be 1×

10⁴ erg/cm³ or less.

26. The magnetic recording method as claimed in claim 24, wherein an axis of easy magnetization of said spin-wave excitation layer is set to be perpendicular to its layer surface.

27. The magnetic recording method as claimed in claim 24, wherein, in a multilayer of said spin-wave excitation layer, a non-magnetic intermediate layer and a magnetization free layer having a magnetization with its direction varied according to external magnetic fields, magnetizations of said spin-wave excitation layer and said magnetization free layer are biased in a direction substantially perpendicular to their layer surfaces by a portion of magnetic field generated from said magnetic pole, and an electric current is applied to said multilayer from the magnetization free layer side to the spin-wave excitation layer side.

28. The magnetic recording method as claimed in claim 24, wherein a frequency of the high frequency electromagnetic field generated from said spin-wave excitation layer is set to be substantially equal to a magnetic resonance frequency of a magnetic recording layer of the magnetic recording medium to be written.

29. The magnetic recording method as claimed in claim 24, wherein the electric current is applied to said spin-wave excitation layer after the write field rises from said magnetic pole, and the electric current is stopped before the write field falls.