Trilayer seed layer structure for spin valve sensor

• US 6,775,111 B2
• Filed: 05/03/2002
• Issued: 08/10/2004
• Est. Priority Date: 10/28/1999
• Status: Expired due to Fees

• Current Assignee: HGST Netherlands B.V. (Western Digital Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Mauri, Daniele, Lin, Tsann
• Primary Examiner(s): Miller, Brian E.
• Application Number:
  US10/138,947
• Publication Number:
  US 20020181170A1
• Time in Patent Office: 830 Days
• Field of Search: 360/324, 360/324.1, 360/324.11
• US Class Current: 360/324.11
• 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 2005/3996 large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: G11B 5/3133 including layers not usually being a part of the electromagnetic transducer structure and providing additional features, e.g. for improving heat radiation, reduction of power dissipation, adaptations for measurement or indication of gap depth or other properties of the structure G11B5/3106 takes precedence
• CPC Class Codes: G11B 5/3163 Fabrication methods or processes specially adapted for a particular head structure, e.g. using base layers for electroplating, using functional layers for masking, using energy or particle beams for shaping the structure or modifying the properties of the basic layers
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: H01F 10/3268 the exchange coupling being asymmetric, e.g. by use of additional pinning, by using antiferromagnetic or ferromagnetic coupling interface, i.e. so-called spin-valve [SV] structure, e.g. NiFe/Cu/NiFe/FeMn
• 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

Abstract

A trilayer seed layer structure is employed between a first read gap layer and a spin valve sensor for improving the magnetic and giant magnetoresistive properties and the thermal stability. In the spin valve sensor, the trilayer seed layer structure is located between a first read gap layer and a ferromagnetic free layer. The antiferromagnetic pinning layer is preferably nickel manganese (Ni—Mn). The trilayer seed layer structure includes a first seed layer that is a first metallic oxide, a second seed layer that is a second metallic oxide and a third seed layer that is a nonmagnetic metal. A preferred embodiment is a first seed layer of nickel oxide (NiO), a second seed layer of nickel manganese oxide (NiMnO_x), and a third seed layer of copper (Cu).

Claims

1. A magnetic read head comprising:

a spin valve sensor including;

a ferromagnetic free layer having a magnetization that is free to rotate from a first direction in response to a signal field;

a ferromagnetic pinned layer having a magnetization;

a nonmagnetic electrically conductive spacer layer sandwiched between the free layer and the pinned layer;

an antiferromagnetic pinning layer in contact with the pinned layer and exchange coupled to the pinned layer for pinning the magnetization of the pinned layer; and

a trilayer seed layer structure comprising;

a first seed layer comprising nickel oxide (NiO);

a third seed layer, comprising copper (Cu), directly underlying and in contact with the ferromagnetic free layer; and

a second seed layer, comprising nickel manganese oxide (NiMnO_x), sandwiched between the first seed layer and the third seed layer.

2. The magnetic read head as recited in claim 1 wherein the first seed layer has a thickness in the range of 100-400 Å

.

3. The magnetic read head as recited in claim 1 wherein the second seed layer has a thickness in the range of 20-40 Å

.

4. The magnetic read head as recited in claim 1 wherein the third seed layer has a thickness in the range of 10-20 Å

.

5. A magnetic head assembly comprising a read head and a write head:

the write head including;

first and second pole piece layers;

each of the first and second pole piece layers having a yoke portion located between a pole tip portion and a back gap portion;

a nonmagnetic write gap layer located between the pole tip portions of the first and second pole piece layers;

an insulation stack with at least one coil layer embedded therein located between the yoke portions of the first and second pole piece layers; and

the first and second pole piece layers being connected at their back gaps portions; and

the read head having a spin valve sensor that includes;

a ferromagnetic free layer having a magnetization that is free to rotate from a first direction in response to a signal field;

a ferromagnetic pinned layer having a magnetization;

a nonmagnetic electrically conductive spacer layer located between the free layer and the pinned layer;

an antiferromagnetic pinning layer in contact with the pinned layer and exchange coupled to the pinned layer for pinning the magnetization of the pinned layer in a second direction; and

a trilayer seed layer structure comprising;

a first seed layer of nickel oxide (NiO);

a third seed layer directly underlying and in contact with the ferromagnetic free layer, said third seed layer selected from a group of materials consisting of copper (Cu), silver (Ag), gold (Au), and their alloys; and

a second seed layer of nickel manganese oxide (NiMnO_x) sandwiched between the first seed layer and the third seed layer;

the read head further including;

first and second hard bias and lead layers connected to first and second side edges of the spin valve sensor;

nonmagnetic electrically insulative first and second read gap layers;

the trilayer seed layer structure, the spin valve sensor and the first and second hard bias and lead layers being located between the first and second read gap layers;

a ferromagnetic first shield layer; and

the first and second read gap layers being located between the first shield layer and the first pole piece layer.

6. A magnetic disk drive having at least one slider that has an air bearing surface (ABS), the slider supporting at least one magnetic head assembly that includes a read head and a write head, the disk drive comprising:

the write head including;

first and second pole piece layers;

each of the first and second pole piece layers having a yoke portion located between a pole tip portion and a back gap portion;

a nonmagnetic write gap layer located between the pole tip portions of the first and second pole piece layers;

an insulation stack with at least one coil layer embedded therein located between the yoke portions of the first and second pole piece layers; and

the first and second pole piece layers being connected at their back gap portions; and

the read head having a spin valve sensor that includes;

a ferromagnetic free layer having a magnetization that is free to rotate from a first direction in response to a signal field;

a ferromagnetic pinned layer having a magnetization;

a nonmagnetic electrically conductive spacer layer located between the free layer and the pinned layer; and

an antiferromagnetic pinning layer adjacent to the pinned layer and exchange coupled to the pinned layer for pinning the magnetization of the pinned layer in a second direction;

a trilayer seed layer structure comprising;

a first seed layer, comprising nickel oxide (NiO);

a third seed layer, selected from the group of materials consisting of copper (Cu), silver (Ag), gold (Au), and their alloys, directly underlying and in contact with the ferromagnetic free layer; and

a second seed layer, comprising nickel manganese oxide (NiMnO_x), sandwiched between the first seed layer and the second seed layer;

the read head further including;

first and second hard bias and lead layers connected to first and second side edges of the spin valve sensor;

nonmagnetic electrically insulative first and second read gap layers;

the trilayer seed layer structure, the spin valve sensor and the first and second hard bias and lead layers being located between the first and second read gap layers;

a ferromagnetic first shield layer; and

the first and second read gap layers being located between the first shield layer and the first pole piece layer; and

a housing;

a magnetic disk rotatably supported in the housing;

a support mounted in the housing for supporting the magnetic head assembly with the ABS facing the magnetic disk so that the magnetic head assembly is in a transducing relationship with the magnetic disk;

a motor for rotating the magnetic disk;

an actuator arm connected to the support for moving the magnetic head assembly to multiple positions with respect to said magnetic disk; and

a processing circuitry connected to the magnetic head assembly, to the motor for rotating the magnetic disk and to the actuator arm for exchanging signals with the magnetic head assembly, for controlling rotation of the magnetic disk and for controlling the position of the magnetic head assembly.