Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2000-11-07
2002-10-15
Cao, Allen (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06466416
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a magnetic head used in a magnetic storage device, a method for making the same, and a magnetic storage device using such magnetic head. More particularly, this invention relates to a giant magnetoresistive (GMR) effect type magnetic head with a magnetic recording head of new structure.
BACKGROUND OF THE INVENTION
As miniaturized magnetic storage devices with large capacity are developed, the volume per one bit recorded on a magnetic medium has rapidly become smaller. A magnetoresistive effect type head (hereinafter referred to as “MR head”) can detect a magnetic signal generated by this micro bit as a larger reproduced output. The MR head is described in IEEE Transactions on Magnetics MAG7 (1971)150, titled “A Magnetoresistivity Readout Transducer”. Further, lately, a giant magnetoresistive effect type head (hereinafter referred to as “GMR effect type head”) using giant magnetoresistive effect (hereinafter referred to as “GMR effect”) which can create significantly higher output than that in the former MR head has been put into practical use.
The GMR effect is classified into several kinds by the difference of mechanism to give a variation in magnetic reluctance. Among them, a magnetoresistive effect generally called spin-valve effect can generate a large variation of resistance by a small operating magnetic field because the variation of resistance corresponds to the cosine between the magnetization directions of two adjacent magnetic layers. Because of this advantage, the GMR effect type head using spin-valve effect has become the main stream of GMR effect type heads now being developed.
The GMR effect type head using spin-valve effect is described in IEEE Transactions on Magnetics, Vol. 30, No. 6 (1994) 3801, titled “Design, Fabrication & Testing of Spin-Valve Read Heads for High Density Recording”. In the GMR head disclosed in this literature, one of two magnetic layers which generate spin-valve effect includes an anti-ferromagnetic film laminated on that magnetic layer. As a result, its magnetization is pinned by exchange coupling field generated between the both so as to be substantially aligned into the magnetic-field direction of a medium which goes into a magneto-sensitive portion of the head, thereby forming a magnetization-pinned layer. The other magnetic layer being located adjacent to the magnetization-pinned layer through a conductive layer such as Cu forms such a magnetization-free layer that can change the direction of magnetization freely to the magnetic field of medium. Since the description below mainly relates to the GMR effect type head using spin-valve effect, the GMR effect type head using spin-valve effect will be hereinafter called “GMR head”.
FIG. 2
is a plan view showing the structure of a GMR head that is seen from an air bearing surface (ABS) opposite to an medium. Also,
FIG. 1
is a cross sectional view, cut along the line A-B of
FIG. 2
, showing the inner structure of the GMR head. The GMR head has such a composite structure that a reproducing element and a writing element are combined. In the GMR reproducing element, a magnetic isolation layer
3
, an insulator, is provided between a laminated layer of lower shied
2
and upper shield
6
on ceramic
1
composing a slider. In its center region
4
, a spin-valve structure which generates GMR effect is allocated, while at the both ends of the center region
4
, terminal regions
5
to supply electric current and bias magnetic field to the spin-valve lamination structure are formed.
Further, while using the upper shield
6
as a first magnetic pole, onto the surface (upper surface) of the first magnetic pole
6
on the opposite side of the GMR element, a second magnetic pole
11
(hereinafter referred to as “upper magnetic pole”) is laminated in parallel to the first magnetic pole
6
through a magnetic gap
7
. As shown in
FIG. 1
, a coil
9
sandwiched by an insulator
8
and an insulator
10
is allocated slightly behind the first magnetic pole
6
and the second magnetic pole
11
. Writing and recording onto the medium are conducted by magnetic flux leaked from the magneto-gap
7
between the first magnetic pole
6
and the second magnetic pole
11
that are magnetized by the magnetic field generated by the coil
9
. This inductive recording head (hereinafter called “ID head”) and the reproducing head by GMR mentioned above form an integrated lamination. In general, practical GMR heads employ a composite structure of the ID head and the reproducing head as shown in FIG.
2
.
On the other hand, conventional type MR heads using magnetic anisotropy have been also improved to get higher density, and have become able to offer a high density up to about 3 gigabit per square inch. To compete with such an improvement, the storage density of GMR heads of the next generation needs to be in a high-density region of more than 3 gigabits per square inch. Therefore, substantially desired are GMR heads that have a high density recording and reproducing of more than 3 gigabits per square. As a result, a magnetic storage device composed using such a GMR head can achieve a high density recording/reproducing device of more than 3 gigabits per square inch.
Also, as the output of reproducing head, although not limited to the GMR head, becomes higher, the ID head that offers the recording function to a magnetic medium also needs the enhancement of recording performance toward higher density. Especially, in a case that such high density recording as mentioned above is conducted, further improvement of magnetic media for a higher coercive force is required. Namely, in raising the storage density, in order to make the transition length of magnetization recorded on magnetic media smaller and also in order to hold magnetization stable even if the transition length of magnetization per bit becomes shorter, it is necessary for the magnetic media to have further high coercive force. Until now, the development to increase the recording magnetic field of ID head itself has been vigorously conducted so as to conform to a magnetic media with high coercive force suited for the high density recording.
Conventionally, as a magnetic core of ID head, a plated film of Ni-Fe with Ni content ratio of about 80% (hereinafter referred to as “80 NiFe”) has been used. It is reported that the 80 NiFe material has a saturation magnetization (Bs) of about 1 T(Tesla) and offers the recording of 3 gigabits per square inch (IEEE Transactions on Magnetics, Vol. 32, No. 1, 1996, pp. 7-12 “3 GB/in
2
recording demonstration with dual element heads & thin film disks”).
Also, it is suggested that in order to conduct the recording of more than 5 gigabits per square inch, instead of the 80 NiFe, for example, the adoption of a NiFe plated film with Ni content ratio of about 45% (hereinafter referred to as “45 NiFe”) is useful (IEEE Transactions on Magnetics, Vol. 33, No. 5, 1997, pp. 2866-2871 “5 GB/in
2
recording demonstration with conventional AMR dual element heads & thin film disks”). The 45 NiFe material has a saturation magnetization of about 1.6 T at the maximum. Further, it is reported that using the 45 NiFe material, the recording of about 12 gigabits per square inch becomes possible (“12 GB/in
2
recording demonstration with SV read heads & conventional narrow pole-tip write”, IEEE Transactions on Magnetics, Vol. 32, No. 1, 1996, pp. 7-12). In addition to these, Japanese patent application Laid-open Nos. 8-212512 and 11-16120 disclose examples using a NiFe plated film with Bs of about 1.6 T.
Other than the NiFe plated film, there are some cases that a high Bs material formed by sputtering is used. For example, Japanese patent application Laid-open No. 10-162322 discloses the use of a Co system amorphous material represented by a CoTaZr sputtered film. The Co system amorphous film can offer a high Bs up to about 1.5 T. Further, Japanese patent application Laid-open No. 7-262519 discloses the application of high Bs material such as iron(III) nitride. The iron-nitrogen system material may off
Honjo Hiroaki
Ishi Tsutomu
Ishiwata Nobuyuki
Nonaka Yoshihiro
Saito Mikiko
Cao Allen
Hayes & Soloway P.C.
NEC Corporation
LandOfFree
Magnetic head, method for making the same and magnetic... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetic head, method for making the same and magnetic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic head, method for making the same and magnetic... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2981675