Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2000-06-14
2003-04-29
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S324200
Reexamination Certificate
active
06556391
ABSTRACT:
The present invention relates generally to a magnetoresistance effect magnetic head that uses a magnetoresistance effect element. More particularly, the invention relates to biasing layers of a magnetoresistance effect magnetic head disposed at ends of the magnetoresistance effect element for improving reproduction of the signal magnetic field from a magnetic recording medium.
BACKGROUND
Referring now to
FIG. 1
, a magnetoresistance effect magnetic head
100
(hereinafter called the magnetic head), for example, is well known.
FIG. 1
shows a cross-section of the overall structure of the magnetic head
100
as it faces the magnetic recording medium (not shown). A magnetoresistance effect element
101
for sensing the signal magnetic field from the magnetic recording medium, such as a hard disk, is shown in the center portion of the magnetic head
100
in
FIG. 1. A
well-known magnetoresistance effect (MR) element
101
is a spin valve magnetoresistance effect (SVMR) element. This spin valve magnetoresistance effect element
101
is typically formed from multiple deposited thin-film layers including a first magnetic layer, a nonmagnetic layer, a second magnetic layer, and an antiferromagnetic layer (not shown).
The magnetoresistance effect element
101
also has ends
101
A,
101
B connected to electrically conductive lead terminals
102
A,
102
B. Hard films
103
A,
103
B are placed under the lead terminals
102
A,
102
B and in contact with the magnetoresistance effect element
101
. The magnetoresistance effect element
101
, the lead terminals
102
A,
102
B, and the hard films
103
A,
103
B are electrically insulated on both the upper and lower sides by an insulating upper gap material
104
and a lower gap material
105
. A top
104
A of the upper gap material
104
and a bottom
105
A of the lower gap material
105
are shielded by soft magnetic shields
106
,
107
, respectively.
Recently, there has been considerable demand for higher density recording in magnetic recording/reproducing equipment. To detect information (signal magnetic field) magnetically recorded at high densities by using the magnetic head
100
, which is very sensitive, the width of the gap W
1
between the shields
106
,
107
was narrowed and the film thickness of the entire magnetic head
100
was thinned. However, the gap materials
104
,
105
must maintain a specific film thickness to maintain its insulating characteristics, and forming thinner gap materials
104
,
105
is difficult and costly.
Thus, referring now to
FIG. 2
, a known magnetic head
200
further narrows a gap width W
2
without narrowing the gap material as disclosed in unexamined Patent Publication (Kokai) No. 9-28807. In the magnetic head
200
, a magnetoresistance effect element
201
is electrically connected to an upper shield
206
and a lower shield
207
, which also function as the lead terminals. This configuration eliminates the need for a gap material
204
between the shield
206
and insulating film
202
A, and between shield
206
and insulating film
202
B, and eliminates the need for gap material
205
between shield
207
and hard film
209
A, and between shield
207
and hard film
209
B to further narrow the gap width W
2
. This, in turn, enables a narrower gap to be fabricated.
The upper and the lower gap materials
204
,
205
placed above and below the magnetoresistance effect element
201
are formed from electrically conductive materials. The insulating films
202
A,
202
B are provided on ends
201
A,
201
B of the magnetoresistance effect element
201
.
Referring again to
FIGS. 1-2
, the flow direction of the sense current for magnetic head
100
is different from the flow direction of the sense current for magnetic head
200
. In the magnetic head
100
, the sense current flows from the lead terminal
102
A through the magnetoresistance effect element
101
to the lead terminal
102
B (or in the reverse direction) in a direction parallel to a generally planar surface
108
of element
101
(only shown in cross section) hereinafter “planar direction”. In the magnetic head
200
, the sense current flows from the upper shield
206
through the magnetoresistance effect element
201
to the lower shield
207
(or in the reverse direction) in a direction perpendicular to a surface
208
of the element
201
, hereinafter “perpendicular direction”. The magnetic head
100
, in which the sense current flows in the planar direction, is called a CIP (Current In Plane) magnetic head. The magnetic head
200
, in which the sense current flows in the perpendicular direction, is called a CPP (Current Perpendicular) magnetic head.
Since the sense current in the CIP magnetic head
100
described above flows in the planar direction, this head cannot use an MR element, for example, that requires the sense current to flow in the perpendicular direction as in a tunnel magnetoresistance effect (TMR) element. In contrast, magnetic heads using CPP are expected to become popular because of the ability of the magnetic head
200
described above to use the TMR element and to narrow the gap W
2
as described above. However, the magnetic head
200
leaks current at both ends
201
A,
201
B of the magnetoresistance effect element
201
, and therefore has difficulty in producing an efficient flow in the perpendicular direction.
To control the magnetic domain of the magnetoresistance effect element
201
, hard films
209
A,
209
B are formed on both ends
201
A,
201
B of the magnetoresistance effect element
201
for applying a longitudinal bias magnetic field (not shown). In this case, however, if the hard films
209
A,
209
B are electrically conductive materials, electrical shorts develop with the upper gap layer
204
, which in turn lowers the yield.
To prevent shorts and current leakage, the conventional material forming the hard films
209
A,
209
B is a magnetic material that is insulating and has a coercive force (Hc) above a specific value, for example, 500 Oe (oersteds). However, this kind of magnetic material is difficult to accurately form on ends
201
A,
201
B of the magnetoresistance effect element
201
. If a hard film does not have the required coercive force, the longitudinal bias magnetic field becomes unstable, and the signal magnetic field from the magnetic recording medium cannot be accurately reproduced.
Thus, a main object of the present invention is to provide an improved magnetoresistance effect magnetic head that does not have substantial leakage of current at the ends of the magnetoresistance effect element.
Another object of the present invention is to provide an improved magnetoresistance capable of applying a sufficiently stable longitudinal bias magnetic field to the magnetoresistance effect element.
Yet another of the present invention is to provide an improved magnetic recording/reproducing apparatus with the improved head.
These and other objects of the present invention are discussed or will be apparent from the detailed description of the invention.
SUMMARY OF THE INVENTION
In one aspect of the present invention, leakage currents in the ends of the magnetoresistance effect element can be suppressed by an insulating antiferromagnetic layer placed next to the ends of the element. When the magnetic layers are placed in contact with the antiferromagnetic layers, unidirectional anisotropic magnetic field is generated by the exchange coupling. The magnetic layers apply a stable longitudinal bias magnetic field to the magnetoresistance effect element. Thus, the bias application layer can apply the needed longitudinal bias magnetic field to the magnetoresistance effect element while maintaining an insulating property.
More specifically, a magnetoresistance effect magnetic head has a magnetoresistance effect element and a biasing portion for applying a longitudinal bias magnetic field to the magnetoresistance effect element on at least one end of the magnetoresistance effect element. The biasing portion includes an insulating antiferromagnetic layer and a magnetic layer in exchange coupling with the
Aoshima Ken-ichi
Noma Kenji
Evans Jefferson
Fujitsu Limited
Greer Burns & Crain Ltd.
LandOfFree
Biasing layers for a magnetoresistance effect magnetic head... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Biasing layers for a magnetoresistance effect magnetic head..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Biasing layers for a magnetoresistance effect magnetic head... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3091805