MAGNETIC HEAD, MAGNETIC SENSOR, AND MAGNETIC RECORDING/REPRODUCING APPARATUS

• US 20130107395A1
• Filed: 10/19/2012
• Published: 05/02/2013
• Est. Priority Date: 10/28/2011
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Nagasawa, Tazumi, Suto, Hirofumi, Kudo, Kiwamu, Sato, Rie, Mizushima, Koichi, Yang, Tao
• Granted Patent: US 8,896,973 B2
• Time in Patent Office: Days
• US Class Current: 360/75
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G11B 2005/3996 large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices
• CPC Class Codes: G11B 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: G11B 5/3932 Magnetic biasing films
• CPC Class Codes: Y10T 428/11 Magnetic recording head
• CPC Class Codes: Y10T 428/1171 with defined laminate structural detail
• CPC Class Codes: Y10T 428/1193 with interlaminar component [e.g., adhesion layer, etc.]

Abstract

A magnetic head according to an embodiment includes: a spin-torque oscillator comprising a first ferromagnetic layer, a second ferromagnetic layer, a third ferromagnetic layer provided on the opposite side of the second ferromagnetic layer from the first ferromagnetic layer, a first nonmagnetic layer provided between the first ferromagnetic layer and the second ferromagnetic layer, a second nonmagnetic layer provided between the second ferromagnetic layer and the third ferromagnetic layer, a first electrode provided on a surface on the opposite side of the first ferromagnetic layer from the first nonmagnetic layer, and a second electrode provided on a surface on the opposite side of the third ferromagnetic layer from the second nonmagnetic layer. Magnetization precession is induced in each of the first through third ferromagnetic layers when current is applied between the first and second electrodes.

Claims

1. A magnetic head comprising

a spin-torque oscillator,

the spin-torque oscillator comprising a first ferromagnetic layer, a second ferromagnetic layer, a third ferromagnetic layer provided on the opposite side of the second ferromagnetic layer from the first ferromagnetic layer, a first nonmagnetic layer provided between the first ferromagnetic layer and the second ferromagnetic layer, a second nonmagnetic layer provided between the second ferromagnetic layer and the third ferromagnetic layer, a first electrode provided on a surface on the opposite side of the first ferromagnetic layer from the first nonmagnetic layer, and a second electrode provided on a surface on the opposite side of the third ferromagnetic layer from the second nonmagnetic layer,

wherein the second ferromagnetic layer and the third ferromagnetic layer are antiferromagnetically coupled to each other via the second nonmagnetic layer, magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer are antiparallel to each other when current is not applied between the first and second electrodes, and magnetization precession is induced in each of the first through third ferromagnetic layers when current is applied between the first and second electrodes.

2. The head according to claim 1, wherein the first ferromagnetic layer and the second ferromagnetic layer are 50 nm or less in size.

3. The head according to claim 1, further comprising a hard bias film configured to apply a magnetic field to make the magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer antiparallel to each other.

4. The head according to claim 1, wherein a magnetic moment of the third ferromagnetic layer is larger than a magnetic moment of the second ferromagnetic layer.

5. The head according to claim 1, wherein current is applied in a direction from the first ferromagnetic layer toward the second ferromagnetic layer.

6. The head according to claim 1, wherein current is applied in a direction from the second ferromagnetic layer toward the first ferromagnetic layer.

7. The head according to claim 1, wherein the first nonmagnetic layer is an insulating layer.

8. The head according to claim 1, wherein each of the first and second electrodes is made of a shield material that shields a magnetic field, and an adjustment layer is provided in at least one of between the first electrode and the first ferromagnetic layer, and between the second electrode and the third ferromagnetic layer.

9. A magnetic sensor comprising:

the magnetic head according to claim 1; and

a monitoring device configured to monitor one of change in amplitude of a high-frequency oscillation voltage generated between the first and second electrodes due to magnetization precession induced in the first through third ferromagnetic layers upon application of current to the magnetic head, and change in oscillation frequency caused by an external magnetic field.

10. The sensor according to claim 9, wherein the first ferromagnetic layer and the second ferromagnetic layer are 50 nm or less in size.

11. The sensor according to claim 9, further comprising a hard bias film configured to apply a magnetic field to make the magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer antiparallel to each other.

12. The sensor according to claim 9, wherein a magnetic moment of the third ferromagnetic layer is larger than a magnetic moment of the second ferromagnetic layer.

13. The sensor according to claim 9, wherein current is applied in a direction from the first ferromagnetic layer toward the second ferromagnetic layer.

14. The sensor according to claim 9, wherein current is applied in a direction from the second ferromagnetic layer toward the first ferromagnetic layer.

15. The sensor according to claim 9, wherein the first nonmagnetic layer is an insulating layer.

16. The sensor according to claim 9, wherein each of the first and second electrodes is made of a shield material that shields a magnetic field, and an adjustment layer is provided in at least one of between the first electrode and the first ferromagnetic layer, and between the second electrode and the third ferromagnetic layer.

17. A magnetic recording/reproducing apparatus comprising:

a magnetic recording medium;

a magnetic head according to claim 1;

a movement control unit configured to control the magnetic recording medium and the magnetic head to move relative to each other while facing each other in a floating or contact state;

a position control unit configured to control the magnetic head to be located in a predetermined recording position on the magnetic recording medium; and

a signal processor configured to process a write signal to be written on the magnetic recording medium and a read signal read from the magnetic recording medium by using the magnetic head.