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Magneto-resistive tunnel junction head with biasing elements abutting free layer extended portions

Imported: 23 Feb '17 | Published: 22 Oct '02

Olivier Redon, Koji Shimazawa, Noriaki Kasahara, Satoru Araki

USPTO - Utility Patents

Abstract

Magneto-resistive tunnel junction head having a tunnel multilayered film with a tunnel barrier layer, a ferromagnetic free layer, and a ferromagnetic pinned layer formed as a sandwich. A magnetic field is applied to the free layer in a longitudinal direction by biasing elements at opposite ends, and a length of the free layer is greater than a length of the pinned layer such that the free layer has portions extending beyond opposite ends of the pinned layer. A head output suitable for ultra-high density recording can be obtained with less reduction of TMR ratio. Selection of the biasing element is flexible. A hard material and also an antiferromagnetic material can be selected and the biasing elements can be disposed on either an upper or lower side of the free layer at a desired distance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a magneto-resistive tunnel junction head according to a preferred embodiment of the present invention;

FIG. 2 is a sectional view showing a magneto-resistive tunnel junction head according to another preferred embodiment of the present invention;

FIG. 3 is a sectional view of a tunnel multilayered film for explaining an example of a preferred ferromagnetic free layer to be used in a magneto-resistive tunnel junction head according to the present invention;

FIG. 4 is a graph showing a relationship between a bias magnetic field applied to a ferromagnetic free layer and relative TMR;

FIGS. 5A to

5C are diagrams for explaining a magneto-resistive tunnel effect according to the present invention;

FIG. 6 is a sectional view of a conventional magneto-resistive tunnel junction head; and

FIGS. 7A and 7B are diagrams for explaining a problem of the conventional head.

Claims

1. A magneto-resistive tunnel junction head comprising:

2. The magneto-resistive tunnel junction head according to claim 2, wherein said biasing layer is located at a predetermined distance from a corresponding one of said at least one longitudinal opposite end of the ferromagnetic pinned layer.

3. The magneto-resistive tunnel junction head according to claim 1, wherein said predetermined distance is set to a length which does not substantially lower a TMR ratio characteristic.

4. The magneto-resistive tunnel junction head according to claim 3, wherein said predetermined distance is set to no less than 0.02 m.

5. The magneto-resistive tunnel junction head according to claim 3, wherein said predetermined distance is set to no less than 0.02 m and no greater than 0.3 m.

6. The magneto-resistive tunnel junction head according to claim 3, wherein said predetermined distance is set to no less than 0.02, m and less than 0.15 m.

7. The magneto-resistive tunnel junction head according to claim 1, wherein said ferromagnetic free layer has a thickness of 20 Å to 500 Å.

8. The magneto-resistive tunnel junction head according to claim 1, wherein said tunnel multilayered film has a multilayered film detection end surface constituting an air bearing surface (ABS).

9. The magneto-resistive tunnel junction head according to claim 1, wherein said ferromagnetic free layer is a synthetic ferrimagnet.

10. The magneto-resistive tunnel junction head according to claim 1, wherein said biasing layer comprises a highly coercive material or an antiferromagnetic material, or comprises a laminate body having an antiferromagnetic layer and at least one ferromagnetic layer.

11. The magneto-resistive tunnel junction head according to claim 1, wherein a pinning layer for pinning magnetization of said ferromagnetic pinned layer is stacked on a surface of said ferromagnetic pinned layer remote from a side thereof abutting said tunnel barrier layer.

12. The magneto-resistive tunnel junction head according to claim 1, wherein said tunnel multilayered film is electrically contacted with a pair of electrodes which are disposed to sandwich said tunnel multilayered film therebetween.

13. The magneto-resistive tunnel junction head according to claim 12, wherein a pair of shield layers are formed to sandwich said pair of electrodes therebetween.

14. The magneto-resistive tunnel junction head according to claim 1, wherein longitudinal opposite ends of said tunnel multilayered film are insulated by insulating layers.