Dual AP pinned GMR head with offset layer

Details Dual AP pinned GMR head with offset layer Dual AP pinned GMR head with offset layer

1999-12-06

2003-02-11

Klimowicz, William (Department: 2652)

Dynamic magnetic information storage or retrieval

Head

Magnetoresistive reproducing head

C360S324120

Reexamination Certificate

active

06519117

ABSTRACT:

FIELD OF INVENTION
The field of invention relates to direct access data storage, generally. More specifically, the invention relates to the improved thermal stability of GMR based SV sensors for use within magnetic heads.
BACKGROUND OF THE INVENTION
Hardware systems often include memory storage devices having media on which data can be written to and read from. A direct access storage device (DASD or disk drive) incorporating rotating magnetic disks are commonly used for storing data in magnetic form. Magnetic heads, when writing data, record concentric, radially spaced information tracks on the rotating disks. Magnetic heads also typically include read sensors that read data from the tracks on the disk surfaces.
In high capacity disk drives, magnetoresistive (MR) read sensors, the defining structure of MR heads, can read stored data at higher linear densities than thin film heads. An MR head detects magnetic field(s) through the change in resistance of its MR sensor. The resistance of the MR sensor changes as a function of the direction of the magnetic flux that emanates from the rotating disk.
One type of MR sensor, referred to as a giant magnetoresistive (GMR) effect sensor, takes advantage of the GMR effect. In GMR sensors, the resistance of the MR sensor varies with direction of flux from the rotating disk and as a function of the spin dependent transmission of conducting electrons between magnetic layers separated by a non-magnetic layer (commonly referred to as a spacer) and the accompanying spin dependent scattering within the magnetic layers that takes place at the interface of the magnetic and non-magnetic layers.
GMR sensors using two layers of magnetic material separated by a layer of GMR promoting non-magnetic material are generally referred to as spin valve (SV) sensors. In an SV sensor, one of the magnetic layers, referred to as the pinned layer, has its magnetization “pinned” by exchange coupling with an antiferromagnetic layer. Due to the relatively high internal ferromagnetic coupling field associated with the pinning layer, the magnetization direction of the pinning layer typically does not rotate from the flux lines that emanate from the rotating disk. The magnetization direction of the other magnetic layer (commonly referred to as a free layer), however, is free to rotate with respect to the flux lines that emanate from the rotating disk.
FIG. 1
shows a type of spin valve sensor commonly referred to as a dual spin valve sensor
100
, having end regions
104
and
106
separated by a central region
102
. A free layer (Free MR layer)
110
(free) is separated from two outer pinned (pinned MR layer) layers
120
(PL
1
) and
130
(PL
2
) by two SV promoting spacer layers
140
(SP
1
) and
150
(SP
2
), respectively. Referring to
FIG. 1B
, the magnetization
121
within the first pinned layer
120
is fixed through exchange coupling with a first antiferromagnetic (AFM
1
) layer
125
. The magnetization
131
within the second pinned layer
130
is fixed through exchange coupling with a second antiferromagnetic (AFM) layer
135
(AFM
2
).
Free layer
110
, spacer layers
140
and
150
, pinned layers
120
and
130
and the AFM layers
125
and
135
are all formed in the central region
102
. Hard bias layers
160
and
170
formed in the end regions
104
and
106
, respectively, longitudinally bias the MR free layer
110
. Leads
180
and
190
formed over hard bias layers
160
and
170
, respectively, provide electrical connections for the flow of the sensing current I
s
from a current source for the MR sensor
100
.
A problem with structures such as or similar to that shown in
FIG. 1
is the effect of the pinned layers
120
,
130
on the free layer
110
. Specifically, as shown in
FIG. 1
, magnetic fields Hd
120, 130
(associated with magnetic poles at pinned layers
120
,
130
) as well as ferromagnetic coupling fields Hfc
120, 130
(associated with “orange peel” coupling between pinned layers
120
,
130
and free layer
110
) from the pinned layers
120
,
130
provide a net bias on the free layer
110
. Typically, the magnetic fields Hd
120, 130
have more strength than the ferromagnetic coupling fields Hfc
120, 130
resulting in an undesirable net field H
110
at free layer
110
. Net field H
110
affects the orientation of magnetic moment within the free layer
110
which adversely affects the MR sensing capability of structure
100
.
SUMMARY OF THE INVENTION
An apparatus, comprising a dual spin valve magnetoresistive structure having a free layer and a spacer layer between the free layer and a pinned layer. The pinned layer is between the spacer layer and the antiferromagnetic layer. There is also an offset layer, where the antiferromagnetic layer is between the offset layer and the pinned layer. The offset layer is tailored to introduce a first magnetic field that reduces a net magnetic field within said free layer.


REFERENCES:
patent: 5287238 (1994-02-01), Baumbert et al.
patent: 5422571 (1995-06-01), Gurney et al.
patent: 5432734 (1995-07-01), Kawano et al.
patent: 5442508 (1995-08-01), Smith
patent: 5508867 (1996-04-01), Cain et al.
patent: 5627703 (1997-05-01), Smith
patent: 5648885 (1997-07-01), Nishioka et al.
patent: 5701223 (1997-12-01), Fontana, Jr. et al.
patent: 5705973 (1998-01-01), Yuan et al.
patent: 5738946 (1998-04-01), Iwaski et al.
patent: 5742162 (1998-04-01), Nepela et al.
patent: 5764056 (1998-06-01), Mao et al.
patent: 5768069 (1998-06-01), Mauri
patent: 5784225 (1998-07-01), Saito et al.
patent: 5825595 (1998-10-01), Gill
patent: 5828529 (1998-10-01), Gill
patent: 5850323 (1998-12-01), Kanai
patent: 5856897 (1999-01-01), Mauri
patent: 5862021 (1999-01-01), Deguchi et al.
patent: 5866212 (1999-02-01), Kurosawa et al.
patent: 5869963 (1999-02-01), Saito et al.
patent: 5872502 (1999-02-01), Fujikata et al.
patent: 6061210 (2000-05-01), Gill
patent: 6122150 (2000-09-01), Gill
patent: 6175475 (2001-01-01), Lin et al.
patent: 409083039 (1997-03-01), None
patent: 9-283816 (1997-10-01), None
patent: 410154618 (1998-06-01), None
patent: 410289421 (1998-10-01), None
patent: 11-103102 (1999-04-01), None
By Tanaka, Shimizu, Kishi, Nagasaka & Oshiki; Dual Spin-Valve With Pd-Pt-Mn Anti-Ferromagnetic Layer; © Sep. 1997; IEEE Transactions on Magnetics, vol. 33, No. 5; Fujitsu Limited, Fujitsu Laboratories Ltd. 10-1 Morinosato-Wakamiya, Atsugi 243-01, Japan.

Affiliated with

Also associated with

Rating

Dual AP pinned GMR head with offset layer does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Dual AP pinned GMR head with offset layer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dual AP pinned GMR head with offset layer will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3145230