Magnetoresistive effect transducer having longitudinal bias layer directly connected to free layer

• US 6,950,290 B2
• Filed: 09/12/2002
• Issued: 09/27/2005
• Est. Priority Date: 11/30/1998
• Status: Expired due to Fees

• Current Assignee: Detroit Diesel Corporation (Mercedes-Benz Group AG)
• Original Assignee: NEC Corporation
• Inventors: Ishi, Tsutomu, Ishiwata, Nobuyuki, Nakada, Masafumi, Hayashi, Kazuhiko, Ohashi, Keishi, Kamijo, Atsushi, Honjou, Hiroaki, Matsutera, Hisao, Tsuge, Hisanao, Fujikata, Jun-Ichi, Ishihara, Kunihiko
• Primary Examiner(s): Chen, Tianjie
• Application Number:
  US10/241,520
• Publication Number:
  US 20030035256A1
• Time in Patent Office: 1,111 Days
• Field of Search: 360/324.12, 360/324.1, 360/324.2, 360/327.3, 360/327.31, 360/327.32, 360/324.11, 360/313, 360/55, 324/252
• US Class Current: 360/324.1
• 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: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G11B 5/00 Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor G11B11/00 and G11B13/00 take precedence
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: G11B 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: G11B 5/3932 Magnetic biasing films
• CPC Class Codes: G11B 5/3967 Composite structural arrangements of transducers, e.g. inductive write and magnetoresistive read G11B5/3906 takes precedence

Abstract

In a magnetoresistive effect transducer including a pinning layer, a pinned layer, a free layer and a non-magnetic layer inserted between the pinned layer and the free layer, a longitudinal bias layer is connected directly to a part of the free layer to apply a bias magnetic field to the free layer, thus biasing a magnetization direction of the free layer so that the magnetization direction of the free layer coincides with that of the longitudinal bias layer.

Claims

1. A magnetoresistive effect transducer comprising:

a pinning layer;

a pinned layer;

a free layer having a bottom surface, a top surface, and an edge surface;

a non-magnetic layer inserted between said pinned layer and said free layer; and

a longitudinal bias layer, connected directly to at least a part of one of;

said top surface of said free layer; and

said bottom surface of said free layer,

said longitudinal bias layer applying a bias magnetic field to said free layer to bias a magnetization direction of said free layer so that the magnetization direction of said free layer coincides with that of said longitudinal bias layer,

a sense current flowing between said pinned layer and said free layer through said non-magnetic layer.

2. The transducer as set forth in claim 1, wherein said non-magnetic layer is made of insulating material, so that said free layer, said pinned layer and said non-magnetic layer form a ferromagnetic tunneling junction (MTJ) structure.

3. The transducer as set forth in claim 1, wherein said non-magnetic layer is made of conductive material, so that said free layer, said pinned layer and said non-magnetic layer form a spin valve structure.

4. The transducer as set forth in claim 1, wherein said free layer is formed on said non-magnetic layer and said non-magnetic layer is formed on said pinned layer,

said free layer having a smaller pattern than said pinning layer.

5. The transducer as set forth in claim 1, wherein said pinning layer is formed on said pinned layer, said pinned layer is formed on said non-magnetic layer, and said non-magnetic layer is formed on said free layer,

said pinning layer having a smaller pattern than said free layer.

6. The transducer as set forth in claim 1, further comprising a pinning layer, formed on an outer surface of said pinned layer, for providing an anisotropic exchange coupling with said pinned layer.

7. The magnetoresistive effect transducer of claim 1, wherein said a pinned layer and said free layer each comprises one of:

NiFe, CoFe, NiFeCo, FeCo, CoFeB, CoZrMo, CoZrNb, CoZr, CoZrTa, CoHf, CoTa, CoTaHf, CoNbHf, CoZrNb, CoHfPd, CoTaZrNb, and CoZrMoNi.

8. A magnetoresistive effect transducer comprising:

a pinning layer;

a pinned layer formed on said pinning layer;

a non-magnetic layer formed on said pinned layer;

a free layer formed on said non-magnetic layer; and

a bias layer formed on an upper surface of said free layer,

said free layer having a smaller pattern that said pinned layer,

a sense current flowing between said pinned layer and said free layer through said non-magnetic layer, wherein said non-magnetic layer comprises an insulating material, so that said pinned layer, said non-magnetic layer, and said free layer form a ferromagnetic tunneling junction (MTJ) structure.

9. The transducer as set forth in claim 8, further comprising an interface control layer, inserted between said free layer and said longitudinal bias layer, for controlling said bias magnetic field.

10. A magnetoresistive effect transducer comprising:

a substrate;

a lower magnetic shield layer formed on said substrate;

a pinning layer formed on said lower magnetic shield layer;

a pinned layer formed on said pinning layer, said pinning layer providing an exchange coupling with said pinned layer;

a non-magnetic layer formed on said pinned layer, said non-magnetic layer being made of one of insulating material and conductive material;

a free layer formed on said non-magnetic layer;

a pair of longitudinal bias layers formed on an upper surface of said free layer;

a pair of insulating layers each formed on one of said longitudinal bias layers; and

an upper magnetic shield layer formed on said free layer and said insulating layers,

a sense current flowing between said pinned layer and said free layer through said non-magnetic layer.

11. The transducer as set forth in claim 10, further comprising:

at least one of a lower electrode layer and an upper electrode layer,

said lower electrode layer being inserted between said lower magnetic shield layer and said pinning layer,

said upper electrode layer being inserted between said free layer and said upper magnetic shield layer.

12. A magnetoresistive effect transducer comprising:

a substrate;

a lower magnetic shield layer formed on said substrate;

a pinning layer formed on said lower magnetic shield layer;

a pinned layer formed on said pinning layer, said pinning layer providing an anisotropic exchange coupling with said pinned layer;

a non-magnetic layer formed on said pinned layer, said non-magnetic layer being made of one of insulating material and conductive material;

a free layer formed on said non-magnetic layer;

a longitudinal bias layer formed on an upper surface of said free layer; and

an upper magnetic shield layer formed on said longitudinal bias layer,

a sense current flowing between said pinned layer and said free layer through said non-magnetic layer.

13. The transducer as set forth in claim 12, further comprising:

at least one of a lower electrode layer and an upper electrode layer,

said lower electrode layer being inserted between said lower magnetic shield layer and said pinning layer,

said upper electrode layer being inserted between said free layer and said upper magnetic shield layer.

14. A magnetoresistive effect transducer comprising:

a substrate;

a lower magnetic shield layer formed on said substrate;

a layer formed on said lower magnetic shield layer, said free layer having a bottom surface, an upper surface, and an edge surface;

a pair of longitudinal bias layers formed on one of a portion of said bottom surface of said free layer and a portion of said top surface of said fee layer;

a patterned non-magnetic layer formed on said free layer between said longitudinal bias layers, said patterned non-magnetic layer being made of one of insulating material and conductive material;

a patterned pinned layer formed on said non-magnetic layer;

a patterned pinning layer, formed on said patterned pinned layer, for providing an exchange coupling with said patterned pinned layer;

a pair of insulating layers formed on said free layer, said longitudinal bias layer on sides of said patterned barrier layer, said patterned pinned layer and said patterned pinning layer; and

an upper magnetic shield layer formed on said patterned pinning layer and said insulating layers,

a sense current flowing between said free layer and said patterned pinned layer through said non-magnetic layer.

15. The transducer as set forth in claim 14, further comprising at least one of a lower electrode layer and an upper electrode layer,

said lower electrode layer inserted between said lower magnetic shield layer and said fee layer,

said upper electrode layer being inserted between said patterned pinning layer and said per magnetic shield layer.

16. A magnetic write/read apparatus including a head slider, a wire head and a read head formed on said head slider, wherein said read head comprises:

a pinned layer;

a free layer;

a non-magnetic layer inserted between said pinned layer and said free layer said non-magnetic layer being made of one of insulating material and conductive material; and

a longitudinal bias layer, connected directly to an area of one of an upper surface and a lower surface of maid free layer, for applying a bias magnetic field to said free layer to bias a magnetization direction of said free layer so that the magnetization direction of said free layer coincides with that of said longitudinal bias layer, wherein a sense current flows between said pinned layer and said free layer through said non-magnetic layer.

17. A method for manufacturing a magnetoresistive effect transducer, said method comprising:

forming a magnetoresistive structure including a pinning layer, a pinned layer, a non-magnetic layer made of one of insulating material and conductive material, and a free layer, said free layer having a bottom surface, a top surface opposite said bottom surface, and an edge surface; and

forming a bias layer on at least a portion of one of;

said top surface of said free layer; and

said bottom surface of said free layer.

18. The method of claim 17, further comprising:

forming an interface control layer between said bias layer and said free layer.