Metal treatment – Process of modifying or maintaining internal physical... – Magnetic materials
Reexamination Certificate
1999-05-19
2001-07-31
Sheehan, John (Department: 1742)
Metal treatment
Process of modifying or maintaining internal physical...
Magnetic materials
Reexamination Certificate
active
06267824
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a magnetoresistive effect composite head and a method of manufacturing the same and, more particularly, to a magnetoresistive effect composite head having a reproducing head portion and a magnetic recording head portion that exploits the magnetoresistive effect and a method of manufacturing the same.
In recent years, as the magnetic recording medium is becoming down-sized and its capacity is becoming large, the relative velocity between the magnetic read head and the magnetic recording medium is becoming small, and therefore an expectation for a magnetoresistive effect head (to be referred to as an MR head hereinafter) whose reproducing output does not depend on tape velocity has become increased. This MR head is described in “A Magnetoresistive Readout Transducer”, IEEE TRANSACTION ON MAGNETICS, VOL. MAG-7, NO. 1, MARCH 1971.
A GMR head which uses the giant magnetoresistive effect (to be referred to as GMR hereinafter) that can realize a further larger increase in output than that from the MR head has come to the forefront of the technology. This GMR head is expected as a next-generation MR head since the magnetoresistive effect in which a change in resistance corresponds to the cosine between the directions of magnetization of two adjacent magnetic layers (generally called “the spin-valve effect”) causes a large change in resistance with a small operating field.
An MR head which uses this spin-valve effect is described in “Design, Fabrication & Testing of Spin-Valve Read Heads for High Density Recording”, IEEE TRANSACTION ON MAGNETICS, VOL. 30, NO. 6, NOVEMBER 1994.
Referring to
FIG. 6
, reference numerals
51
and
52
denote two magnetic layers at a central region
116
in an ideal state that causes the spin-valve effect. By the exchange coupling that is obtained upon stacking an antiferromagnetic film
53
on this magnetic layer
51
, the magnetic layer
51
turns itself into a magnetic pinned layer
51
in which its direction of magnetization is substantially aligned with the direction of the medium field which enters the head sensor portion. The other magnetic layer
52
which is adjacent to the magnetic pinned layer
51
via a conductive layer, e.g., a Cu layer, serves as a magnetic free layer
52
whose direction of magnetization is free to change in response to the medium field. Reference numerals
52
A and
52
B denote permanent magnets whose directions of magnetization are constant;
12
and
18
, magnetic shields; and P
1
and P
2
, magnetic poles. This stacked structure that produces the spin-valve effect is used as the major portion of a conventional magnetoresistive effect composite head shown in FIG.
7
.
The conventional magnetoresistive effect composite head (to be abbreviated as the composite head hereinafter) shown in
FIG. 7
will be described. The composite head shown in
FIG. 7
has a slider main body
111
made of a ceramic material, and a pair of magnetic shields
112
and
118
stacked on the slider main body
111
and opposing each other through a predetermined gap. Stacked magnetic spacer layers
113
and
117
made of insulators are formed between the magnetic shields
112
and
118
. A central region
116
and end regions
114
and
115
are formed in the magnetic spacer layers
113
and
117
. The central region
116
is a stacked structure which produces the spin-valve effect. The end regions
114
and
115
are located on the two sides of and on the same plane as that of the central region
116
to supply a current and a bias field to the central region
116
. Reference numeral
120
denotes a protection film made of alumina or the like. A magnetoresistive effect element
110
formed of the central region
116
and end regions
114
and
115
constitutes a reproducing head that reads.
Of the magnetic shields
112
and
118
, the upper shield
118
forms one magnetic pole P
1
. The other magnetic pole P
2
is stacked, on a surface of the magnetic pole P
1
which is opposite to the central region
116
, via a magnetic gap
119
to lie parallel to the magnetic pole P
1
(upper shield
118
).
A coil (not shown) sandwiched by insulators is arranged slightly behind the magnetic poles P
1
and P
2
. A magnetic flux leaking from the magnetic gap
119
between the magnetic poles P
1
and P
2
that are magnetized by the magnetic field generated by this coil performs recording. A structure in which this recording head and the reproducing head described above are stacked constitutes a practical magnetoresistive effect composite head that makes use of the spin-valve effect.
In this case, as shown in
FIG. 6
that indicates the ideal state, the direction of magnetization of one of the two adjacent magnetic layers must be locked to be parallel to the medium field so that this magnetic layer becomes a magnetic pinned layer
51
, and the other magnetic layer becomes a magnetic free layer
52
the magnetization of which is free to rotate in response to the medium field. This is indispensable in realizing appropriate head operation.
The direction of magnetization of this magnetic pinned layer is perpendicular to the easy axis of magnetization of the magnetic shields (upper and lower shields) constituting the composite head and of the magnetic poles of the inductive head (ID head) that records. When a heat magnetic field treatment is performed to stabilize the magnetization of the spin-valve magnetic pinned layer at the central region, the magnetic anisotropy of the magnetic shields and of the respective recording magnetic poles is reversed. In contrast, when a heat magnetic field treatment is performed to stabilize the magnetic anisotropy of the magnetic shields and of the recording magnetic poles, the magnetization of the spin-valve magnetic pinned layer becomes unstable. These problems present a large obstacle to putting a composite head made of a spin-valve element into practical use.
SUMMARY OF THE INVENTIONn
It is an object of the present invention to provide a magnetoresistive effect composite head in which the operation of a reproducing MR head portion and a recording ID head portion using a spin-valve element and constituting a composite head is stabilized, and a method of manufacturing the same.
In order to achieve the above object, according to the present invention, there is provided a magnetoresistive effect composite head comprising a reproducing head portion having a pair of magnetic shields and a magnetoresistive effect element, the pair of magnetic shields opposing each other on a slider main body made of a ceramic material through a predetermined gap, and the magnetoresistive effect element being sandwiched and stacked between the magnetic shields with a magnetic spacer layer made of an insulator, and a recording head portion using one of the magnetic shields as a first magnetic pole and having a second magnetic pole formed on a surface of the first magnetic pole opposite to the magnetoresistive effect element through a magnetic gap, the recording head portion recording information on a recording medium by means of a magnetic field generated in the magnetic gap, wherein the magnetoresistive effect element includes a central region made of a spin-valve element to sense a medium field, and end regions for supplying a bias field and a current to the central region, and the second magnetic pole is constituted by a stacked film of first and second magnetic films having different saturation magnetizations, the first magnetic film being close to the magnetic gap and the second magnetic film being far from the magnetic gap, and the saturation magnetization of the first magnetic film being set to a value larger than that of the second magnetic film.
REFERENCES:
patent: 5503686 (1996-04-01), Okamura et al.
patent: 5606478 (1997-02-01), Chen et al.
patent: 5772794 (1998-06-01), Uno et al.
patent: 6123781 (2000-09-01), Shimazawa
patent: 61-258323 (1986-01-01), None
patent: 1-150212 (1989-06-01), None
patent: 4-358310 (1992-12-01), None
patent: 5-347013 (1993-12-01), None
patent: 6-68420 (1994-
Ishi Tsutomu
Ishiwata Nobuyuki
Kumagai Kazumasa
Nagahara Kiyokazu
NEC Corporation
Sheehan John
Sughrue Mion Zinn Macpeak & Seas, PLLC
LandOfFree
Method for manufacturing a magnetoresistive effect composite... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for manufacturing a magnetoresistive effect composite..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for manufacturing a magnetoresistive effect composite... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2561166