FERROMAGNETIC TUNNEL JUNCTION ELEMENT, MAGNETIC RECORDING DEVICE AND MAGNETIC MEMORY DEVICE

• US 20090097170A1
• Filed: 09/02/2008
• Published: 04/16/2009
• Est. Priority Date: 10/16/2007
• Status: Abandoned Application

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Sato, Masashige, Ibusuki, Takahiro, Umehara, Shinjiro
• Application Number:
  US12/202,789
• Publication Number:
  US 20090097170A1
• Time in Patent Office: Days
• US Class Current: 360/324.12
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G11B 5/3906 Details related to the use of magnetic thin film layers or to their effects
• CPC Class Codes: G11B 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: G11C 11/1657 Word-line or row circuits
• CPC Class Codes: G11C 11/1659 Cell access
• CPC Class Codes: H01F 10/3204 Exchange coupling of amorphous multilayers
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• 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 10/3295 Spin-exchange coupled multilayers wherein the magnetic pinned or free layers are laminated without anti-parallel coupling within the pinned and free layers
• CPC Class Codes: H10B 61/22 of the field-effect transistor [FET] type
• CPC Class Codes: H10N 50/85 Magnetic active materials

Abstract

A ferromagnetic tunnel junction element is a magnetoresistance effect element wherein an electric resistance varies in accordance with a magnetic field applied. The ferromagnetic tunnel junction element includes a pinned layer wherein at least a part of a magnetization direction is held, and an insulation layer formed on the pinned layer, creating an energy barrier that electrons can flow through by a tunnel effect. A first free layer made of a first ferromagnetic material containing boron atoms, is formed on the insulation layer. In the first free layer, a direction of the magnetization switches under an influence of an external magnetic field. A second free layer made of a first ferromagnetic material containing boron atoms, is formed on the first free layer. The direction of magnetization of the second free layer switches under the influence of the external magnetic field, exchanging and coupling with the first free layer.

Claims

1. A ferromagnetic tunnel junction element, comprising:

a pinned layer wherein at least a part of a magnetization direction is held;

an insulation layer formed on the pinned layer, creating an energy barrier that electrons can flow through by a tunnel effect;

a first free layer formed on the insulation layer made of a first ferromagnetic material containing boron atoms, wherein a direction of the magnetization switches under an influence of an external magnetic field; and

a second free layer made of a second ferromagnetic material containing boron atoms formed on the first free layer, wherein the direction of the magnetization switches under the influence of the external magnetic field, exchanging and coupling with the first free layer.

2. The ferromagnetic tunnel junction element according to claim 1, wherein the second ferromagnetic material is amorphous.

3. The ferromagnetic tunnel junction element according to claim 1, wherein the second ferromagnetic material contains 10-25 at % of boron atoms.

4. The ferromagnetic tunnel junction element according to claim 1, wherein the first ferromagnetic material contains 10-25 at % of boron atoms.

5. The ferromagnetic tunnel junction element according to claim 1, wherein the first ferromagnetic material contains Co atoms and Fe atoms.

6. The ferromagnetic tunnel junction element according to claim 1, wherein a coercitivity of the second free layer is lower than that of the first free layer.

7. The ferromagnetic tunnel junction element according to claim 1, wherein the ferromagnetic material contains Ni atoms and Fe atoms.

8. The ferromagnetic tunnel junction element according to claim 7, wherein a proportion of the Ni atoms to Fe atoms is 85 at % of greater.

9. The ferromagnetic tunnel junction element according to claim 1, wherein the insulation layer is crystalline.

10. The ferromagnetic tunnel junction element according to claim 1, wherein the insulation layer contains magnesia oxide partially crystallized.

11. A magnetic recording device comprising:

a magnetic recording medium for information recording/reproduction; and

a head slider for recording/reproducing information onto/from the magnetic recording medium, laid out against the magnetic recording medium,

wherein the head slider comprises;

a magnetic head having a pinned layer in which at least a part of the magnetization direction is held in one specific direction;

an insulation layer formed on the pinned layer, creating an energy barrier that electrons can flow through by the tunnel effect;

a first free layer formed on the insulation layer, wherein the direction of the magnetization switches under the influence of the external magnetic field, made of a first ferromagnetic material containing boron atoms;

a tunnel junction element having a second free layer made of a second ferromagnetic material containing boron atoms formed on the first free layer, wherein the direction of the magnetization switches under the influence of an external magnetic field, exchanging and coupling with the first free layer, made of the second ferromagnetic material containing boron atoms.

12. A magnetic memory device comprising:

a pinned layer wherein at least a part of a magnetization direction is held in one specific direction;

an insulation layer formed on the pinned layer, creating an energy barrier that electrons can flow through by the tunnel effect;

a first free layer formed on the insulation layer made of a first ferromagnetic material containing boron atoms, wherein the direction of the magnetization switches under the influence of the external magnetic field;

the ferromagnetic tunnel junction element having a second free layer formed on the first free layer made of a second ferromagnetic material containing boron atoms, wherein the direction of the magnetization switches under the influence of the external magnetic field, exchanging and coupling with the first free layer, a writing means for applying a magnetic field to the ferromagnetic tunnel junction element to switch the directions of the magnetizations of the first and second free layers in specific directions; and

a reading means for detecting a tunnel resistance value by applying a sense current to the ferromagnetic tunnel junction element.