Magnetic sensing device including a sense enhancing layer

• US 7,800,868 B2
• Filed: 12/16/2005
• Issued: 09/21/2010
• Est. Priority Date: 12/16/2005
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Karr, Brian W., Xue, Song, Gao, Zheng, Tran, Khuong T., Li, Yi X., Granstrom, Eric L.
• Primary Examiner(s): Miller; Brian E
• Assistant Examiner(s): Dravininkas; Adam B
• Application Number:
  US11/305,778
• Publication Number:
  US 20070139827A1
• Time in Patent Office: 1,740 Days
• Field of Search: 360/324.12, 360/324.2
• 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: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• 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: 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: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: Y10T 428/1114 having tunnel junction effect
• CPC Class Codes: Y10T 428/1121 Multilayer

Abstract

A magnetic sensor includes a sensor stack having a first magnetic portion, a second magnetic portion, and a barrier layer between the first magnetic portion and the second magnetic portion. At least one of the first magnetic portion and the second magnetic portion includes a multilayer structure having a first magnetic layer having a positive magnetostriction adjacent to the barrier layer, a second magnetic layer, and an intermediate layer between the first magnetic layer and the second magnetic layer. The magnetic sensor has an MR ratio of at least about 80% when the magnetic sensor has a resistance-area (RA) product of about 1.0 Ω·μm².

Claims

1. A magnetoresistive (MR) sensor having improved sensitivity comprising:

a first magnetic structure;

a MgO barrier layer adjacent to the first magnetic structure; and

a second magnetic structure adjacent to the MgO barrier layer on a side opposite the first magnetic structure, the second magnetic structure including a positive magnetostriction layer adjacent to the barrier layer, a negative magnetostriction layer, and a sense enhancing layer between the positive magnetostriction layer and the negative magnetostriction layer,

wherein the second magnetic structure comprises one of a free layer and a reference layer, and

wherein the MR sensor is characterized by an MR ratio of (a) at least about 30% with a resistance-area (RA) product of about 0.5 Ω

·

μ

m², (b) at least about 50% with an RA product of about 0.8 Ω

·

μ

m², (c) at least about 80% with an RA product of about 1.0 Ω

·

μ

m², or (d) at least about 100% with an RA product of about 1.4 Ω

·

μ

m².

2. The magnetic sensor of claim 1, wherein the sense enhancing layer comprises a material selected from the group consisting of Ta, Ru, Zr, Hf, Nb, Mo, W, Pt, Rh, Ir, Al, Cu, Cr, Ti, CoZrNb, CoZrTa, FeTa, FeTaN, NiFeZr, CoFeTa, CoNb, and alloys thereof.

3. The magnetic sensor of claim 1, wherein the sense enhancing layer comprises a non-magnetic material and has a thickness in a range of about 0.5 Å

to about 10 Å

.

4. The sensor stack of claim 1, wherein the positive magnetostriction layer comprises a material selected from the group consisting of CoFeB, CoFeNiB, CoFe, and alloys thereof.