Magnetoresistance effect element and magnetoresistance device

A magnetoresistance effect element according to the present invention comprises magnetic multilayer film having a non-magnetic metal layer, a ferromagnetic layer formed on one surface of the non-magnetic metal layer, a soft magnetic layer formed on the other surface of the non-magnetic metal layer, and a pinning layer which is formed on the ferromagnetic layer to pin a direction of magnetization of the ferromagnetic layer, wherein the ferromagnetic layer and the pinning layer are coupled to each other with epitaxial growth.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a magnetoresistance effect element for 
reading the magnetic field intensity of magnetic recording media as 
signals, especially a magnetoresistance effect element capable of reading 
a small magnetic field change as a greater electrical resistance change 
signals, and a magnetoresistance device such as a magnetoresistance effect 
type head or the like using the same. 
2. Prior Art 
There are recently growing demands for increasing the sensitivity of 
magnetic sensors and increasing the density of magnetic recording, and 
active research works have been devoted for the development of 
magnetoresistance effect type magnetic sensors (hereinafter referred to as 
MR sensors) and magnetoresistance effect type magnetic heads (hereinafter 
referred to as MR heads). Both MR sensors and MR heads are designed to 
read out external magnetic field signals on the basis of the variation in 
resistance of a reading sensor portion formed of magnetic material. The MR 
sensors have an advantage that a high sensitivity can be obtained and the 
MR heads have an advantage that a high output can be obtained in high 
density magnetic recording because the reproduced output does not depend 
on the relative speed of the sensors or heads to the recording medium. 
However, conventional MR sensors which are formed of magnetic materials 
such as Ni.sub.0.8 Fe.sub.0.2 (Permalloy), NiCo or the like have a small 
magnetoresistance change .DELTA.R/R which is about 1 to 3% at maximum, and 
thus these materials have insufficient sensitivity as the reading MR head 
materials for ultrahigh density recording of the order of several giga bit 
per square inch (GBPI) or more. 
Attention has been recently paid to artificial superlattices having the 
structure in which thin films of metal having a thickness of an atomic 
diameter order are periodically stacked, because their behavior is 
different from that of bulk metal. One of such artificial superlattices is 
a magnetic multilayer film having ferromagnetic metal thin films and 
antiferromagnetic metal thin films alternately deposited on a substrate. 
Heretofore, magnetic multilayer films of iron-chromium and cobalt-copper 
types have been known. Among these materials, the iron-chromium (Fe/Cr) 
type was reported to exhibit a magnetoresistance change which exceeds 40% 
at an extremely low temperature (4.2K) (see Phys. Rev. Lett., Vol. 61, 
p2472, 1988). However, this artificial superlattice magnetic multilayer 
film is not commercially applicable if it is left as it is because the 
external magnetic field at which a maximum resistance change occurs (that 
is, operating magnetic field intensity), is as high as ten to several tens 
of kilo-oersted. Additionally, there have been proposed artificial 
superlattice magnetic multilayer films of Co/Ag, which require too high 
operating magnetic field intensity. 
Under these circumstances, a new structure which is called as a spin valve 
film is proposed. In this structure, two NiFe layers are formed through a 
non-magnetic layer, and an FeMn layer is further formed so as to be 
adjacent to one of the NiFe layers. In this case, since the FeMn layer and 
the NiFe layer adjacent thereto are directly exchange-coupled to each 
other, the direction of the magnetic spin of this NiFe layer is fixed in 
the range of several tens to several hundreds Oe in magnetic field 
intensity. On the other hand, the direction of the magnetic spin of the 
other NiFe layer is freely varied by an external magnetic field. As a 
result, there can be achieved a magnetoresistance change rate (MR ratio) 
in a small range of 2 to 5%, which corresponds to the degree of coercive 
force of the NiFe layer. In addition, the following papers have been 
published. 
a. Physical Review B, 43(1991)1297 
Si/Ta(50)/NiFe(60)/Cu(20)/NiFe(45)/FeMn(70)/Ta(50) 
parenthesis represents film thickness (.ANG.) of each layer! is reported 
to exhibit that its MR ratio sharply rises up to 5.0% at an applied 
external magnetic field of 10 Oe. 
b. Journal of Magnetism and Magnetic Materials, 93(1991)101 
Si/Ta(50)/NiFe(60)/Cu(25)/NiFe(40)/FeMn(50)/Cu(50) is reported to exhibit 
that its MR ratio sharply rises up from 0 to 4.1% at an applied external 
magnetic field of 0 to 15 Oe. 
c. Physical Review B, 45(1992)806 
The temperature characteristics and MR characteristics when the magnetic 
layer thickness is varied and Co, NiFeNi, etc. are used as the magnetic 
layer are analyzed on the basis of the results of the above papers a and 
b. 
d. Japanese Journal of Applied Physics, 32(1993)L1441 
The MR ratio is reported when the multilayer structure is adopted in the 
above papers a and b. In this multilayer structure, the structure of 
NiFe(60)/Cu(25)/NiFe(40)FeMn(50) is laminated so as to sandwich Cu 
therebetween. 
Furthermore, the following publications are made public. 
e. Japanese Laid-open Patent Application No. Hei-2-61572 (U.S. Pat. No. 
4,949,039) 
It is described that a large MR effect can be obtained by forming 
ferromagnetic thin films through a non-magnetic intermediate layer so as 
to be arranged in anti-parallel to each other. In addition, it describes a 
structure in which antiferromagnetic material is disposed adjacently to 
one of the ferromagnetic layers. 
f. Japanese Laid-open Patent Application Hei-5-347013 
A magnetic recording and reproducing device using a spin valve film is 
described. Particularly, it is disclosed that nickel oxide is used for an 
antiferromagnetic film. 
In such a spin valve magnetic multilayer film, the MR ratio is lower than 
the structure of Fe/Cr, Co/Cu, Co/Ag or the like , however, the MR curve 
varies sharply at an applied magnetic field below several tens Oe, so that 
it is suitably usable as MR head material for a recording density higher 
than 1 to 10 Gbit/inch.sup.2. However, these papers and publications 
merely disclose the basic action of the spin valve film. 
Ni.sub.0.8 Fe.sub.0.2 (Permalloy) is mainly used as the MR head material 
for actual ultrahigh density magnetic recording at present. This material 
converts the change of a signal magnetic field from a magnetic recording 
medium into the change of electrical resistance by utilizing an 
anisotropic magnetoresistance effect. The MR ratio is in the range of 1 to 
3% at most. In this case, the magnetoresistance change has a 
characteristic which is symmetrical at increasing and decreasing sides of 
magnetic field with the magnetic field of zero at the center. 
As a means of solving this characteristic, in case of NiFe, etc., a shunt 
layer of Ti or the like which has a low resistivity is provided to shift 
an operating point. Furthermore, in addition to the shunt layer, a soft 
film bias layer which is formed of soft magnetic material having a large 
resistivity such as CoZrMo, NiFeRh or the like is also provided to apply a 
bias magnetic field. However, the structure having such a bias layer 
complicates its manufacturing process, and makes it difficult to stabilize 
its characteristics, resulting in cost-up. Furthermore, in this case, a 
gently-sloping portion of an MR change curve which is caused by the shift 
of the MR curve is used, and thus the MR slope per unit magnetic field is 
reduced to a small value of about 0.05%/Oe, resulting in reduction of S/N. 
Therefore, this value is insufficient as the MR head material for the 
recording density higher than 1 to 10 Gbit/inch.sup.2. 
Furthermore, in case of MR heads, etc., there are some cases where a 
laminate structure is complicated, and thermal treatments such as baking, 
curing, etc. of resist materials are required in a patterning process, a 
flattening process, etc., so that heat resistance against a temperature of 
about 300.degree. C. is required for MR materials. However, such a thermal 
treatment deteriorates the characteristics of the conventional artificial 
superlattice structure. 
With respect to the conventional spin valve film as disclosed in the 
papers, etc., only the basic structure and basic characteristics thereof 
as a thin film are argued, and any MR head structure to realize the 
ultrahigh density recording and any magnetic multilayer structure suitable 
therefor are not described. 
As described above, in the examples as described in these papers, when the 
thin films as described in these papers are applied as an MR head, the MR 
slope is small in an actual magnetic field detection range, and thus an 
excellent and stable reproduced output cannot be obtained by the MR head. 
Furthermore, an MR change curve at an applied magnetic field of -10 to 10 
Oe is important as a more excellent MR head material in the ultrahigh 
density magnetic recording. However, any of these papers has no argument 
on the details of the MR slope in this range. 
Furthermore, a high-density recording and reproducing MR head is required 
to be used under high-frequency magnetic field above 1 MHz. However, in 
the film-thickness structure of each type conventional three-element 
magnetic multilayer, it is difficult to set above 0.2%/Oe of the slope (MR 
slope at a high frequency) of a magnetoresistance change curve at a width 
of 10 Oe in the high frequency magnetic field range above 1 MHz to obtain 
high sensitivity at high frequencies. 
SUMMARY OF THE INVENTION 
The present invention has been achieved in view of the above situation, and 
its object is to provide a magnetoresistance effect element with a 
magnetic multilayer film having a high heat-resistance, which has a high 
MR ratio, characteristic of exhibiting linear rise-up of MR change in an 
extremely small magnetic-field range of about -10 to 10 Oe, high 
sensitivity to magnetic field and a large MR slope under a high-frequency 
magnetic field, and also to provide a magnetoresistance device having the 
magnetoresistance effect element, such as a magnetoresistance effect type 
head or the like. 
A magnetoresistance effect element according to the present invention 
comprises a non-magnetic metal layer, a ferromagnetic layer formed on one 
surface of the mon-magnetic metal layer, a soft magnetic layer formed on 
the other surface of the non-magnetic metal layer, and a pinning layer 
which is formed on the ferromagnetic layer to pin the direction of 
magnetization of the ferromagnetic layer, wherein the ferromagnetic layer 
and the pinning layer are coupled to each other by epitaxial growth. 
A magnetoresistance effect element according to the present invention has a 
magnetic multilayer film having a magnetic multilayer film unit in which a 
pinning layer for pinning the direction of magnetization of ferromagnetic 
layers adjacent thereto is provided, and a pair of ferromagnetic layers, a 
pair of non-magnetic metal layers and a pair of soft magnetic layers are 
successively laminated at both sides of the pinning layer in this order, 
wherein the ferromagnetic layers and the pinning layer are coupled to each 
other by epitaxial growth. 
A magnetoresistance device according to the present invention comprises a 
magnetoresistance effect element, conductive films and electrode portions, 
wherein the conductive films are conducted to the magnetoresistance effect 
element through the electrode portions, and the magnetoresistance effect 
element comprises a non-magnetic metal layer, a ferromagnetic layer formed 
on one surface of the non-magnetic metal layer, a soft magnetic layer 
formed on the other surface of the non-magnetic metal layer, and a pinning 
layer which is formed on the ferromagnetic layer to pin the direction of 
magnetization of the ferromagnetic layer, wherein the ferromagnetic layer 
and the pinning layer are coupled to each other by epitaxial growth. 
A magnetoresistance device according to the present invention comprises a 
magnetoresistance effect element, conductive films and electrode portions, 
wherein the conductive films conducted to the magnetoresistance effect 
element through the electrode portions, the magnetoresistance effect 
element has a magnetic multilayer film having a magnetic multilayer film 
unit in which a pinning layer for pinning the direction of magnetization 
of ferromagnetic layers adjacent thereto is provided, and a pair of 
ferromagnetic layers, a pair of non-magnetic metal layers and a pair of 
soft magnetic layers are successively laminated at both sides of the 
pinning layer in this order, and the ferromagnetic layers and the pinning 
layer are coupled to each other by epitaxial growth. 
According to the present invention on the first magnetoresistance effect 
element, multilayer films having the magnetoresistance ratio whose MR 
slope is above 0.3%/Oe can be obtained. In addition, the rise-up 
characteristic of the MR curve under zero magnetic field is extremely 
excellent, and has a high heat resistant property. According to the 
present invention on the second magnetoresistance effect element, the MR 
slope further has a higher value above 0.3%/Oe and a low resistivity. In 
addition, there can be obtained a magnetic multilayer film having high 
heat resistance in which no deterioration occurs in its characteristics 
even when a thermal treatment at a temperature before and after 
350.degree. C. is conducted under a pressure of 10.sup.-7 Torr or less. 
According to the present invention on the first magnetoresistance device 
having the first magnetoresistance effect element, an output voltage which 
is approximately three times as high as that of the conventional materials 
can be obtained. Furthermore, according to the second magnetoresistance 
device having the second magnetoresistance effect element, the MR slope in 
a high-frequency region has a high value of 0.3%/Oe or more and a low 
resistivity. In addition, a calorific value due to measurement current is 
small, and an output voltage of 3.8 times can be obtained. Accordingly, 
there can be provided an excellent magnetoresistance device such as an MR 
head which has extremely high reliability, and can perform an ultrahigh 
density magnetic recording operation whose recording density exceeds 1 
Gbit/inch.sup.2.

DETAILED DESCRIPTION OF THE INVENTION 
The embodiments according to the present invention will be described in 
detail. 
FIG. 1 is a cross-sectional view showing a magnetoresistance effect element 
3 of a first embodiment according to the present invention. The 
magnetoresistance effect element 3 has an artificial superlattice magnetic 
multilayer film 1 (hereinafter merely referred to as first magnetic 
multilayer film or magnetic multilayer film 1). In FIG. 1, the magnetic 
multilayer film 1 has a laminate body structure which comprises a 
non-magnetic metal layer 30, a ferromagnetic layer 40 formed on one 
surface of the non-magnetic metal layer 30, a soft magnetic layer 20 
formed on the other surface of the non-magnetic metal layer 30, and a 
pinning layer 50 which is formed on the ferromagnetic layer 40 to pin the 
direction of magnetization of the ferromagnetic layer 40. 
The laminate body structure is usually formed on a substrate 5 as shown in 
FIG. 1, and a metal undercoat layer 10 is interposed between the substrate 
5 and the soft magnetic layer 20. Further, a protection layer 80 is formed 
on the pinning layer 50 as shown in FIG. 1. 
In this invention, it is required that the soft magnetic layer 20 and the 
ferromagnetic layer 40 which are formed at both sides of the non-magnetic 
metal layer 30 so as to be adjacent to the non-magnetic metal layer 30 
have substantially different magnetization directions from each other in 
accordance with a signal magnetic field applied from the external. The 
reason is as follows. In the principle of the present invention, when the 
magnetization directions of the soft magnetic layer 20 and the 
ferromagnetic layer 40 which are formed through the non-magnetic metal 
layer 30 are deviated from each other, conduction electrons have a 
behavior of scattering due to spins to increase its resistance. In this 
case, when the magnetization directions are opposite to each other, the 
maximum resistance is obtained. That is, in this invention, when a signal 
magnetic field from the external is positive (in a upward direction with 
respect to the recording surface 93 of a recording medium 90 (represented 
by reference numeral 92)) as shown in FIG. 2, there occurs components in 
the neighboring magnetic layers whose magnetization directions are 
opposite to each other, so that the resistance is increased. 
Here, the relationship among the external signal magnetic field from a 
magnetic recording medium, magnetization directions of the soft magnetic 
layer 20 and the ferromagnetic layer 40 and the variation of electrical 
resistance will be described. 
Now, in order to facilitate the understanding of the present invention, a 
simplest magnetic multilayer film I in which a pair of a soft magnetic 
layer 20 and a ferromagnetic layer 40 exist through a non-magnetic metal 
layer 30 as shown in FIG. 2 will be described with reference to FIG. 2. 
As shown in FIG. 2, the magnetization of the ferromagnetic layer 40 is 
pinned in a downward direction to the surface of the recording medium by a 
method as described later (reference numeral 41). The soft magnetic layer 
20 is formed through the non-magnetic metal layer 30, so that the 
magnetization direction thereof is varied in accordance with the signal 
magnetic field from the external (reference numeral 21). At this time, the 
relative angle between the magnetization directions of the soft magnetic 
layer 20 and the ferromagnetic layer 40 is greatly varied in accordance 
with the direction of the signal magnetic field from the magnetic 
recording medium 90. As a result, the scattering degree of the conduction 
electrons flowing in the magnetic layers is varied, and thus the 
electrical resistance is greatly varied. 
Accordingly, a large MR (Magneto-Resistive) effect, which is substantially 
different in mechanism from the anisotropic magnetoresistance effect of 
ordinary permalloy, can be obtained. 
The magnetization directions of the soft magnetic layer 20, the 
ferromagnetic layer 40 and the pinning layer 50 exhibiting a pinning 
effect are varied relatively to the external magnetic field. The variation 
of the magnetization directions thereof is shown in FIG. 3 in 
correspondence with the magnetization curve and the MR curve. In this 
case, all the magnetization of the ferromagnetic layer 40 is fixed in a 
minus direction (in a downward direction with respect to the recording 
surface of the recording medium 90). When the external signal magnetic 
field is minus, the magnetization of the soft magnetic layer 20 is in the 
minus direction. Now, it is assumed that the coercive force of each of the 
soft magnetic layer 20 and the ferromagnetic layer 40 is approximate to 
zero in order to simplify the description. In an area (I) where the signal 
magnetic field H&lt;0, the magnetization of both the soft magnetic layer 20 
and the ferromagnetic layer 40 is in a fixed direction. However, when the 
external magnetic field is intensified and H exceeds the coercive force of 
the soft magnetic layer 20, the magnetization direction of the soft 
magnetic layer is rotated in the direction of the signal magnetic field, 
so that the magnetization and the electrical resistance are increased as 
the magnetization directions of the soft magnetic layer 20 and the 
ferromagnetic layer 40 are opposite to each other. Finally, these values 
are fixed (the state of an area (II)). At this time, a pinning magnetic 
field Hex is applied by the pinning layer 50. If the signal magnetic field 
exceeds Hex, the magnetization of the ferromagnetic layer 40 is also 
rotated in the direction of the signal magnetic field, so that the 
magnetization of each of the soft magnetic layer 20 and the ferromagnetic 
layer 40 is oriented in the same fixed direction in an area (III). At this 
time, the magnetization is set to a constant value, and the MR curve is 
equal to zero. 
Conversely, when the signal magnetic field H is reduced, the magnetization 
is changed from the area (III) through the area (II) to the area (I) by 
inversion of the magnetization of the soft magnetic layer 20 and the 
ferromagnetic layer 40 in the same manner as described above. At an 
initial portion of the area (II), conduction electrons have a behavior of 
scattering dependently on spins, and the resistance is increased. In the 
area (II), there ferromagnetic layer 40 has little magnetization inversion 
because it is pinned, however, the magnetization of the soft magnetic 
layer 20 increases linearly, so that the rate of spin-dependently 
scattered conduction electrodes is gradually increased in accordance with 
the magnetization change of the soft magnetic layer 20. That is, if 
Ni.sub.0.8 Fe.sub.0.2 whose Hc is low is selected for the soft magnetic 
layer 20 and a suitable anisotropic magnetic field Hk is applied, a formed 
magnetic multilayer film has a linearly-varying resistance and a large 
magnetoresistance ratio in a small external magnetic field of several Oe 
to several tens Oe below Hk. 
In this invention, the thickness of each thin film layer is set to an 
individual limit value. If the thickness of the non-magnetic metal layer 
is larger than the limit value, the rate of the conduction electrodes 
flowing through only this layer increases, so that the total MR change 
becomes small unfavorably. On the other hand, the conduction electrodes 
are scattered at the interface portions between the non-magnetic metal 
layer and each of the soft magnetic layer 20 and the ferromagnetic layer 
40, so that the effect is not substantially improved even if the thickness 
of the two magnetic layers 20, 40 is larger than 10 .ANG.. Rather, it is 
unfavorable because the total film thickness is increased. The lower limit 
of the thickness of the two magnetic layers 20 and 40 is preferably set to 
20 .ANG. or more. If the thickness is smaller than this value, heat 
resistance and resistance against processing are deteriorated. 
Each construction of the first magnetic multilayer film as described above 
will be described hereunder in detail. 
This multilayer film is first characterized in that the ferromagnetic layer 
40 and the pinning layer 50 are laminated on each other epitaxially 
(epitaxy). That is, the ferromagnetic layer 40 and the pinning layer 50 as 
described above are formed so as to be coupled to each other by epitaxial 
growth. 
The epitaxy is a word which expresses a phenomenon on crystal growth 
between layers. In this invention, respective atoms of both the pinning 
layer 50 and the ferromagnetic layer 40 which is formed to be adjacent to 
the pinning layer 50 are aligned with one another to some extent on a 
crystal orientation face, and also these layers are formed in a 
crystallographic relationship with each other. In this invention, the 
magnetic multilayer film thus formed is cut out in a laminate direction, 
and the laminate section is observed with a high-resolution transmission 
electron microscope (TEM). The inside of the ferromagnetic layer 40 and 
the inside of the pinning layer 50 are observed. If any crystal lattice 
fringe is observed, the crystal orientation of the layer is found out to 
be aligned, and the orientation face(or plane) is identified on the basis 
of the interval thereof. Next, the interface portion between the pinning 
layer 50 and the ferromagnetic layer 40 is observed in detail. If the 
interference fringes of the respective layers are connected to each other 
at the interface portion, these layers are judged to be in an epitaxy 
relationship with each other. 
As described above, according to the present invention, it is an important 
requirement that the ferromagnetic layer 40 and the pinning layer 50 are 
coupled to each other by epitaxial growth. If these layers 40 and 50 are 
not formed by the epitaxial growth, the pinning effect of the 
ferromagnetic layer 40 by the pinning layer 50 is reduced, and thus no 
relative angle occurs between the spins of the soft magnetic layer 20 and 
the ferromagnetic layer 40, so that there occurs a disadvantage that no 
large electrical resistance change occurs. 
The ferromagnetic layer 40 is formed of metal element such as Fe, Ni, Co, 
Mn, Cr, Dy, Er, Nd, Tb, Tm, Ce, Gd or the like, alloy or compound 
containing the above metal element, or the like. Particularly, it is 
preferably formed of a composition expressed by (Co.sub.z 
Ni.sub.1-z).sub.w Fe.sub.1-w (0.4.ltoreq.z.ltoreq.1.0, 
0.5.ltoreq.w.ltoreq.1.0 by weight). Out of the composition range as 
described above, no large electrical resistance change can be obtained. 
The thickness of the ferromagnetic layer as described above is set to 20 to 
100 .ANG., and more preferably 20 to 60 .ANG.. If this value is smaller 
than 20 .ANG., it loses the characteristic as the ferromagnetic layer. On 
the other hand, if the value exceeds 100 .ANG., the pinning force of the 
pinning layer 50 is reduced, and thus the sufficient spinning effect of 
the spin of the ferromagnetic layer cannot be obtained. 
Any material may be used as the pinning layer 50 insofar as it fixes the 
magnetization of the ferromagnetic layer to which the pinning layer is 
substantially adjacent. Particularly, it is be selected from an 
antiferromagnetic layer, a hard magnetic layer, a pinning ferromagnetic 
layer which is formed of material different from the ferromagnetic layer 
40 connected to the pinning layer, and a layer into which artificial 
structural defects are introduced. 
The antiferromagnetic layer may contain at least two kinds of Fe, Ni, Co, 
Cr, Mm, Ru, Rh, Mo, O. For example, it is preferably selected from FeMn, 
FeMnPt, FeMnRu, FeMnRh, FeMnMo,FeNiO, CoNiO, CrMn, CrMnO, Fe.sub.2 
O.sub.3, NiO, etc. 
As the hard magnetic layer is preferably selected material which is formed 
of one kind of metal selected from Fe, Co and Ni,or contains 50 at % or 
more of one kind of metal selected from Fe, Co and Ni. For example, FeNi, 
CoNi, FeTb, CoPt, CoFePt or the like is preferable. 
As the ferromagnetic layer formed of different material is used Fe, Ni, Co, 
Mn, Cr, Dy, Er, Nd, Tb, Tm, Ce, Gd or the like, or alloy or compound which 
contains these elements. For example, it is preferably formed of FeSi, 
FeNi, FeCo, FeAl, FeAlSi, FeY, FeGd, FeMn, CoNi, CrSb, Fe-based amorphous 
alloy, Co-based amorphous alloy, MnSb, NiMn, ferrite or the like. 
The same pinning effect can be obtained by introducing artificial 
structural defects into the interface portion of the ferromagnetic layer 
40 which faces the pinning layer 50. In this case, after the ferromagnetic 
layer 40 is formed, the surface of the ferromagnetic layer 40 at a 
thickness of about 2 to 20 .ANG. is etched by weak ion beams at an ion 
current of 10 to 50 mA and at an acceleration voltage of about 100 to 500 
eV. At this time, the magnetization of the ferromagnetic layer 40 is 
pinned by the introduced structural defects at the interface portion, and 
the same effects as the other methods can be obtained. 
With this method, since the ferromagnetic layer 40 and the pinning layer 50 
which are adjacent to each other are substantially directly contacted with 
each other, a direct interlayer interaction acts on each other, and the 
rotation of the magnetization of the ferromagnetic layer 40 is prevented. 
On the other hand, with respect to the soft magnetic layer 20 as described 
in detail later, its magnetization can freely rotated by a signal magnetic 
field from the outside. As a result, a relative angle between both the 
soft magnetic layer 20 and the ferromagnetic layer 40 is produced, so that 
a large MR effect due to the difference between the magnetization 
directions can be obtained. 
The thickness of the pinning layer 50 is preferably set to 50 to 700 .ANG.. 
If the thickness is smaller than 50 .ANG., the crystallinity of the 
pinning layer is lowered, and the sufficient pinning effect cannot be 
obtained, so that the large MR effect cannot be obtained. If the thickness 
exceeds 700 .ANG., the total thickness of the magnetic multilayer film is 
excessively large, and thus the total resistance of the film is large, so 
that the MR ratio is reduced. In addition, the thickness of the shield 
layer is larger, and thus the multilayer film thus formed is unsuitable 
for the ultrahigh magnetic recording. 
The soft magnetic layer 20 is formed of Fe, Ni, Co or the like, or alloy or 
compound containing these elements. The MR curve rises up more sharply by 
using the magnetic layer having small coercive force Hc, and a favorable 
effect can be obtained. Particularly, a composition as expressed by 
(Ni.sub.x Fe.sub.1-x).sub.y Co.sub.1-y (0.7.ltoreq.x.ltoreq.0.9, 
0.5.ltoreq.y.ltoreq.1.0 by weight) is preferable. Here, if x, y are within 
these ranges, Hc becomes small and excellent soft magnetic characteristics 
can be obtained, so that an excellent MR characteristic having high 
magnetic field sensitivity can be obtained. On the other hand, if x, y are 
out of these ranges, Hc becomes large, so that no MR characteristic having 
high magnetic field can be obtained unfavorably. 
Furthermore, as the composition of the soft magnetic layer 20, the 
composition as expressed by Co.sub.t M.sub.u M'.sub.q B.sub.r 
(0.6.ltoreq.t.ltoreq.0.95, 0.01.ltoreq.u.ltoreq.0.2, 
0.01.ltoreq.q.ltoreq.0.1, 0.05.ltoreq.r.ltoreq.0.3 by atomic ratio) also 
exhibits an excellent characteristic. Here, M comprises at least one kind 
selected from Fe and Ni, and M' comprises at least one kind selected from 
Zr, Si, Mo and Nb. When M and M' comprises at least two kinds of 
materials, the total amount of at least the two kinds are set to be within 
the above composition range. Such a composition contains a large amount of 
Co, so that it has an extremely excellent advantage that the MR ratio is 
larger than the composition as described above. Furthermore, it has a 
crystal structure in which ultrafine crystal particles are assembled or an 
amorphous structure, and thus it exhibits an excellent soft magnetic 
characteristic, so that the large MR slope can be obtained. As a specific 
composition, Co is contained as a main component and the amount of Ni 
and/or Fe is set so that magnetostriction is equal to zero. Further, Zr, 
Si, Mo, Nb or the like is added to this composition to stabilize the 
amorphous composition. If the composition ratio of Co is lower than 0.6, 
no amorphous state can be obtained. The composition ratio of Co may exceed 
0.95, and a small amount of Fe or Ni is preferably added because an 
excellent characteristic as the soft magnetic material can be obtained. 
The composition ratio of M' is set to 0.01.ltoreq.q.ltoreq.0.1, and no 
effect of the addition of M' can be obtained if q is lower than 0.01. If q 
exceeds 0.1, the characteristic as the soft magnetic material is 
deteriorated. B (boron) is the main element to make amorphous, and its 
composition ratio is set to 0.05.ltoreq.r.ltoreq.0.3. If r is lower than 
0.05, no effect of the addition of B can be obtained. If r exceeds 0.3, 
the characteristic as the soft magnetic material is deteriorated. 
The thickness of the soft magnetic layer 20 as described above is set to 20 
to 100 .ANG., preferably 40 to 100 .ANG., and more preferably 50 to 80 
.ANG.. If this value is smaller than 20 .ANG., no excellent characteristic 
as the soft magnetic layer can be obtained. On the other hand, if the 
value exceeds 100 .ANG., the total thickness of the multilayer film is 
large and the resistance of the whole magnetic multilayer film is 
increased, so that the MR effect is reduced. 
In order to conduct electrons efficiently, a metal having conductivity is 
preferably used for the non-magnetic metal layer which is interposed 
between the soft magnetic layer 20 and the ferromagnetic layer 40. More 
specifically, it may formed of at least one kind selected from Au, Ag and 
Cu, alloy containing 60 wt% or more of at least one of these elements, or 
the like. 
The thickness of the mon-magnetic metal layer 30 is preferably set to 20 to 
60 .ANG.. If this value is smaller than 20 .ANG., the soft magnetic layer 
20 and the ferromagnetic layer 40 which are disposed through the 
non-magnetic metal layer are exchange-coupled to each other, so that the 
spins of the soft magnetic layer 20 and the ferromagnetic layer 40 do not 
function independently of each other. If this value exceeds 60 .ANG., the 
rate of the electrons which are scattered at the interface between the 
soft magnetic layer 20 and the ferromagnetic layer 40 disposed at the 
upper and lower sides respectively are reduced, so that the MR ratio is 
reduced. 
Furthermore, in the relationship among the pinning layer 50, the 
ferromagnetic layer 40 and the soft magnetic layer 20, it is preferable 
that the following resistivity relationship satisfies the following 
equation (1), where the resistivity of the pinning layer 50 is represented 
by .rho..sub.p ; the resistivity of the ferromagnetic layer 40, 
.rho..sub.f ; and the resistivity of the soft magnetic layer 20, 
.rho..sub.s : 
EQU 3((.rho..sub.f +.rho..sub.s)/2)&lt;.rho..sub.p &lt;30((.rho..sub.f 
+.rho..sub.s)/2) equation(1) 
If the value .rho..sub.p is below the lower limit of the equation (1), 
there occurs a disadvantage that the paths of electrons cannot be 
effectively separated. If the value .rho..sub.p, is above the upper limit 
of the equation (1), a manufacturing method is extremely difficult. 
The metal undercoat layer 10 is not limited to a specific one, however, 
preferably it has the same crystal structure as the used non-magnetic 
metal layer 30. That is, Ta, Hf, Cu, Au, Ag, Nb or Zr which has 
face-centered cubic lattice (fcc), alloy of these metals or the like can 
be used for the metal undercoat layer 10. The metal undercoat layer 10 is 
formed to improve the crystal orientation of the whole magnetic multilayer 
film. The thickness thereof is set to about 30 to 300 .ANG.. 
The protection layer 80 is formed to prevent oxidation of the surface of 
the magnetic multilayer film in a film-forming process and improve 
wettability with electrode material formed thereon and adhesive strength. 
The protection layer 80 is formed of Ti, Ta, W, Cr, Hf, Zr, Zn or the 
like. The thickness thereof is generally set to about 30 to 300 .ANG.. 
The substrate 5 is formed of glass, silicon, MgO, GaAs, ferrite, AlTiC, 
CaTiO.sub.3 or the like, and the thickness thereof is generally set to 
about 0.5 to 10 mm. 
Next, a magnetoresistance effect element of a second embodiment according 
to the present invention, that is, a magnetoresistance effect element 4 
having a magnetic multilayer film as shown in FIG. 4 (hereinafter merely 
referred to as a second magnetic multilayer film or magnetic multilayer 
film 2) will be described. 
The magnetic multilayer film 2 of the magnetoresistance effect element 4 of 
the second embodiment has a magnetic multilayer unit comprising a pair of 
ferromagnetic layers 40, a pair of non-magnetic metal layers 30 and a pair 
of soft magnetic layers 20 which are successively disposed at both sides 
of a pinning layer 50 as shown in FIG. 4. In this embodiment, the unit 7 
is formed on a substrate 5 through a metal undercoat layer 10 as shown in 
FIG. 4. Further, the protection layer 80 is formed on the soft magnetic 
layer 20 at the upper side as shown in FIG. 4. A non-magnetic metal layer 
may be formed between the metal undercoat layer 10 and the soft magnetic 
layer 20. In FIG. 4, the same reference numerals as used for the 
description of the magnetic multilayer film 1 (FIG. 1) represent the same 
members as those of the magnetic multilayer film 1 as described above, and 
they have the same basic actions. 
The inventors has made further progress in their studies on the 
construction of the magnetic multilayer film 1 (FIG. 1) having the 
magnetoresistance effect element 3 of the first embodiment as described 
above, and through these studies, they have found out that the 
construction of a magnetic multilayer film 2 as shown in FIG. 4 is 
particularly preferable to obtain a large MR effect. 
That is, the pinning layer 50 has a magnetic spin structure which is 
substantially fixed in a direction against an external magnetic field. The 
magnitude of the spin is not varied by the external signal magnetic field. 
On the other hand, the magnetic multilayer film of the present invention 
exhibits great magnetoresistance change by changing the direction of the 
spin of the soft magnetic layer 20 relatively to the signal magnetic 
field. Accordingly, in order to increase the magnetoresistance, the number 
of the soft magnetic layers 20 whose spins are freely rotated is set to be 
higher than the number of pinning layers 50. That is, as shown in FIG. 4, 
the ferromagnetic layers 40,40, the non-magnetic metal layers 30, 30 and 
the soft magnetic layers 20, 20 may be formed at both sides of the pinning 
layer 50 with the pinning layer 50 at the center of the multilayer film as 
shown in FIG. 4 to form the magnetic multilayer film 2 (magnetoresistance 
effect element 4) having a greatly-improved magnetoresistance effect. 
It is preferable that the ferromagnetic layers 40, the non-magnetic metals 
30, the soft magnetic layers 20 and the pinning layer 50 are formed of the 
same materials as the first embodiment and at the same thickness as the 
first embodiment. The same is also applied to the protection layer 80, the 
metal undercoat layer 10 and the substrate 5. In the magnetic multilayer 
film 2 as described above, the pinning layer 50 and the pair of 
ferromagnetic layers 40 which are formed at both sides of the pinning 
layer 50 are required to be coupled to each other by the epitaxial growth. 
The spins of both the ferromagnetic layers 40, 40 and the soft magnetic 
layers 20, 20 contribute to the scattering of the conduction electrons. 
When both the spins have substantially the same magnitude, the electrons 
are scattered most efficiently. That is, it is best that the magnetization 
amount of each layer is set to substantially the same value. However, in 
the case of the magnetic multilayer film 2 of the second embodiment, The 
ferromagnetic layers 40, 40 are designed to be formed at both sides of the 
pinning layer 50. Accordingly, considering only one ferromagnetic layer 
40, the scattering is performed with higher efficiency by setting the 
magnetization of the ferromagnetic layer 40 to be smaller than the 
magnetization of the soft magnetization layer 20. If the ferromagnetic 
layer 40 has an excessively large thickness, the magnetization of the 
whole layer 40 becomes larger than the magnetization of the soft magnetic 
layer 20, so that the thickness of the ferromagnetic layer 40 is set to 
such a value that both the layers have substantially the same 
magnetization. Specifically, if the thickness of each of the layers 20 and 
40 is set to satisfy the following equation: 
EQU 0.3 Ms.ltoreq.Mf0.8 Ms, preferably 0.4 Ms.ltoreq.Mf.ltoreq.0.7 Ms, 
where the magnetization of the ferromagnetic layer 40 is represented by Mf 
and the magnetization of the soft magnetic layer 20 is represented by Ms, 
the relationship between the thickness of each layer and the scattering 
efficiency has the best balance. 
The material of each layer and the thickness thereof are specified as 
described above, and an external magnetic field is applied in a direction 
within the film surface as described later at the film formation time of 
at least the soft magnetic layer 20 to apply anisotropic magnetic field Hk 
of 3 to 20 Oe, preferably 3 to 16 Oe, and more preferably 3 to 12 Oe. With 
this operation, the magnetic multilayer film 2 (magnetoresistance effect 
element 4) thus formed has an MR change curve in which the MR slope at a 
rise-up portion is equal to 0.3%/Oe or more, particularly 0.4%/Oe or more, 
usually 0.4 to 1.0%/Oe. The maximum hysteresis width of the MR change 
curve is equal to 8 Oe or less, usually 0 to 6 Oe. Furthermore, the MR 
slope under the high-frequency magnetic field of 1 MHz can be set to 
0.2%/Oe or more, more preferably 0.25%/Oe or more, usually 0.3 to 1.0%/Oe. 
Accordingly, when it is used for a reading MR head or the like for the 
high-density recording, a sufficient performance can be obtained. In the 
magnetic multilayer film 1 of the first embodiment (magnetoresistance 
effect element 3), it is better to conduct the same treatment on the soft 
magnetic layer 20. If the anisotropic magnetic field Hk of the soft 
magnetic layer is lower than 3 Oe, it is equal to the same degree of the 
coercive force, and no linear MR change curve can be substantially 
obtained in the vicinity of zero magnetic field, so that the 
characteristic as the MR element is deteriorated. On the other hand, If it 
is higher than 20 Oe, the MR slope becomes small and when this film is 
applied to the MR head or the like, the output is liable to be reduced and 
the resolution is reduced. The value ilk as described above can be 
obtained by applying the external magnetic field of 10 to 300 Oe at the 
film formation, If the external magnetic field is below 10 Oe, it is too 
insufficient to induce Hk. On the other hand, if it exceeds 300 Oe, the 
effect is not improved although a coil must be designed in a large size 
due to occurrence of magnetic field. Therefore, the cost is increased and 
thus it is inefficient. 
When the maximum resistivity is represented by .rho..sub.max and the 
minimum resistivity is represented by .rho..sub.sat, the MR ratio is 
represented as (.rho..sub.max -.rho..sub.sat).times.100/.rho..sub.sat (%). 
The maximum hysteresis width corresponds to the maximum value of the 
hysteresis width which is calculated by measuring the magnetoresistance 
change curve (MR curve). The MR slope corresponds to the maximum value of 
differential values at -20 to +20 Oe which is obtained by measuring the MR 
curve and calculating a differential curve. The high-frequency MR slope 
corresponds to an MR slope which is obtained by measuring the MR ratio 
under an alternating current magnetic field of 6 Oe magnetic width at 1 
MHz. 
Each of the magnetic multilayer film 1 of the first embodiment and the 
magnetic multilayer film 2 of the second embodiment may be repetitively 
laminated to form a magnetoresistance effect element. In this case, the 
repetitive lamination frequency N of the magnetic multilayer film is not 
limited to a specific one, and it may be suitably selected in accordance 
with a desired magnetoresistance ratio, etc. In order to satisfy a present 
requirement for ultrahigh densification of the magnetic recording, the 
total film thickness of the magnetic multilayer film is better to be 
smaller. However, if the film is thinner, the MR effect is usually 
reduced. The magnetic multilayer film of this invention is sufficiently 
practically used, even when the repetitive lamination frequency is equal 
to 1. Furthermore, as the lamination frequency is heightened, the 
magnetoresistance ratio increases, however, productivity is lowered. If N 
is excessively large, the resistance of the whole element is excessively 
low, and it is practically inconvenient. Therefore, usually, N is 
preferably set to 10 or less. The long-period structure of superlattices 
can be confirmed on the basis of appearance of primary and secondary peaks 
in accordance with a repetitive period in a small-angle X-ray diffraction 
pattern. When it is applied to a magnetoresistance device such as an MR 
head or the like for ultrahigh density magnetic recording, N is preferably 
set to 1 to 5. 
The film formation of each layer of the magnetic multilayers 1 and 2 as 
described above may be performed by a ion-beam sputtering method, a 
sputtering method, a deposition method, a molecular beam epitaxy (MBE) 
method or the like. As the substrate 5, glass, silicon, MgO, GaAs, 
ferrite, AlTiC, CaTiO.sub.3 or the like, may be used . For the film 
formation, it is preferable that an external magnetic field of 10 to 300 
Oe is applied in a direction within the film plane at the film formation 
of the soft magnetic layer 20. With this operation, Hk can be provided to 
the soft magnetic layer 20. The application of the external magnetic field 
may be performed at only the film formation time of the soft magnetic 
field, for example, using a device which is equipped with electromagnet or 
the like which is capable of easily controlling an application timing of 
the magnetic field, and no external magnetic field is applied at the film 
formation time of the pinning layer 50. Alternatively, a method of 
applying a constant magnetic field at the film formation time at all times 
may be used. 
Next, the invention of the magnetoresistance effect element having the 
magnetic multilayer film 1 as described in the first embodiment has been 
developed and a path through which electrons flow has been considered in 
detail, thereby achieving the invention of a first magnetoresistance 
device. The magnetoresistance device as described here comprises a 
magnetoresistance effect element, conductive films and electrode portions. 
More specifically, it is a device which is expressed with a broad 
conception covering a magnetoresistance effect type head (MR head), an MR 
sensor, a ferromagnetic memory element, an angle sensor or the like. 
In the following description, a magnetoresistance effect type head (MR 
head) will be picked up and described as an example of the 
magnetoresistance device. 
As shown in FIG. 5, a first magnetoresistance effect type head (MR head) 
150 comprises a magnetoresistance effect element 200 serving as a 
magnetically-sensitive portion for magnetically sensitizing a signal 
magnetic field, and electrode portions 100, 100 which are formed at both 
end portions 200a, 200a of the magnetoresistance effect element 200. 
Preferably, the whole both end portions 200a, 200a of the 
magnetoresistance effect element 200 serving as the magnetically-sensitive 
portion are connected to the electrode portions 100, 100. Conductive films 
120, 120 are electrically conducted to the magnetoresistance effect 
element 200 through the electrode portions 100, 100. In this invention, 
the conductive film 120 and the electrode portion 100 are separately 
provided to simplify the description which will be made later, however, in 
most cases the conductive film 120 and the electrode portion 100 are 
originally formed integrally with each other by a thin film forming 
method. Accordingly, these elements may be considered as being formed of 
one member. 
The magnetoresistance effect element 200 serving as the 
magnetically-sensitive portion of the first MR head has substantially the 
same laminate structure as the magnetoresistance effect element 3 having 
the magnetic multilayer film 1 shown in FIG. 1. That is, the 
magnetoresistance effect element 200 is replaced by the magnetoresistance 
effect element 3 having the magnetic multilayer film 1 shown in FIG. 1, so 
that the magnetoresistance effect element 200 comprises a non-magnetic 
metal layer 30, a ferromagnetic layer 40 formed on one surface of the 
non-magnetic metal layer 30, a soft magnetic layer 20 formed on the other 
surface of the non-magnetic metal layer 30,and a pinning layer 50 formed 
on the ferromagnetic layer 40 to pin the magnetization direction of the 
ferromagnetic layer 40. The ferromagnetic layer 40 and the pinning layer 
50 are coupled to each other by the epitaxial growth. 
As shown in FIG. 5, shield layers 300, 300 are formed so as to sandwich the 
magnetoresistance effect element 200 and the electrode portions 100, 100 
at the upper and lower sides, and a non-magnetic insulation layer 400 is 
formed at a portion between the magnetoresistance effect element 200 and 
the shield layers 300, 300. 
The same material and thickness as the film 1 used in the embodiment of the 
first magnetic multilayer film are preferably used for each of the 
ferromagnetic layer 40, the non-magnetic metal layer 30, the soft magnetic 
layer 20 and the pinning layer 50. 
Here, the detailed consideration has been made on the path of electrodes 
flowing in the magnetic multilayer film of the magnetoresistance effect 
element 200, and as a result of the consideration, it has been found out 
that the electrons as current intensively flow through a certain portion 
in the magnetic multilayer film. That is,the pinning layer 50 is formed of 
material having large resistivity in the magnetic multilayer film. For 
example, FeMn has an extremely low resistivity of 100 to 200 
.mu..OMEGA.cm. Accordingly, the electrons intensively flow through the 
soft magnetic layer 20 and the non-magnetic metal layer 30 each having a 
low resistivity. In a conventional MR head, an NiFe layer serving as a 
magnetically-sensitive portion is formed, and then an electrode is formed 
on the upper surface of the NiFe layer. In this structure, the electrode 
is contacted with the pinning layer having a large resistivity, so that it 
is difficult for current to flow effectively. Furthermore, contact 
resistance is large and the yield on the manufacturing process is reduced. 
These problems can be solved by designing the current-flowing electrode 
portions 100 so that both end portions 200a, 200a thereof are wholly 
contacted with the magnetoresistance effect element 200 in the laminate 
direction as shown in FIG. 5. That is, the electrons intensively flow 
through the portion sandwiched between the soft magnetic layer 20 and the 
ferromagnetic layer 40. At this time, the electrons are magnetically 
scattered in accordance with the spin directions of the soft magnetic 
layer 20 and the ferromagnetic layer 40, so that the resistance is greatly 
varied. Accordingly, a fine change of the external magnetic field can be 
detected as a large change of electrical resistance. 
Furthermore, the invention of the magnetoresistance effect element having 
the magnetic multilayer 2 as described with reference to FIG. 4 has been 
developed, and an embodiment of a second MR head which is a 
magnetoresistance device having two or more current-flowing paths with the 
pinning layer 50 at the center will be described. The basic construction 
of this embodiment is identical to that shown in FIG. 5, and a 
magnetoresistance effect element 200 having a magnetic multilayer film 
serving as a magnetically-sensitive portion has substantially the same 
laminate structure as the magnetoresistance effect element 4 having the 
magnetic multilayer film 2 shown in FIG. 4. That is, in FIG. 5, it may be 
considered that the magnetoresistance effect element 200 is substantially 
replaced by the magnetoresistance effect element 4 having the magnetic 
multilayer film 2 shown in FIG. 4. Both end portions 200a, 200a of the 
magnetoresistance effect element 200 are wholly contacted with the 
electrode portions 100. That is, the whole portion of the 
magnetoresistance effect element 200 in the laminate direction are 
contacted with the electrode portions. 
The specific structure of the magnetoresistance effect element 200 in the 
second MR head will be described with reference to FIG. 4. The magnetic 
multilayer film of the magnetoresistance effect element 200 are 
constructed by successively laminating on a substrate 5 a metal undercoat 
layer 10, a soft magnetic layer 20, a non-magnetic metal layer 30, a 
ferromagnetic layer 40, a pinning layer 50, a ferromagnetic layer 40, a 
non-magnetic metal layer 30, a soft magnetic layer 20 and a metal 
protection layer 80. The pinning layer 50 and the pair of the 
ferromagnetic layers 40 are coupled to each other by the epitaxial growth. 
The electrons flow in the multilayer film with a quantum probability 
because the thickness of each layer is extremely thin. That is, the 
electrons flows through the whole portion in the multilayer film in 
probability, however, the rate of the electrons flowing in a layer having 
a large resistivity is necessarily low. In general, the resistivity of the 
pinning layer 50 is two times or more as high as the non-magnetic metal 
layer 30 and the soft magnetic layer 20. For example, FeMn which is 
antiferromagnetic material has a resistivity of 100 to 200 .mu..OMEGA.cm, 
and FeNi which is soft magnetic material has an extremely small 
resistivity of 15 to 30 .mu..OMEGA.cm. Accordingly, the electrons 
intensively flow into the soft magnetic layer 20 and the non-magnetic 
metal layer 30 each having a low resistivity. In this case, the 
ferromagnetic layers 40, the non-magnetic metal layers 30 and the soft 
magnetic layers 20 are disposed substantially symmetrically with respect 
to the pinning layer 50 of large resistivity which is located at the 
center. Accordingly when the electrons flow in the multilayer film, there 
are two paths through which the electrons flow, the pinning layer 50 
serving as a boundary between the two paths. As described above, the 
electrons flow through the whole portion in the multilayer film in 
probability, and thus at least two paths through which the electrons flow 
can be formed by disposing the layers of large resistivity in a suitable 
arrangement. As a result, the number of electrons which are magnetically 
scattered by the magnetization which are set to be in antiparallel to each 
other by the external magnetic field is increased, and thus a larger MR 
effect can be obtained than in the case where substantially only one 
current path is provided. 
At this time, in order to form at least two paths in which electrons 
substantially flow, it is preferable that the resistivity relationship 
among the pinning layer 50, the ferromagnetic layer 40 and the soft 
magnetic layer 20 satisfies the following equation (1), where the 
resistivity of the pinning layer 50 is represented by .rho..sub.p ; the 
resistivity of the ferromagnetic layer 40, .rho..sub.f ; and the 
resistivity of the soft magnetic layer 20, .rho..sub.s : 
EQU 3((.rho..sub.f +.rho..sub.s)/2)&lt;.rho..sub.p &lt;30((.rho..sub.f 
+.rho..sub.s)/2) equation(1) 
The number of the paths through which the electrons substantially flow is 
preferably equal to 2 to 10. This may be performed by forming the 
multilayer film containing one to four pinning layers 50 in the same 
structure as described above. When three paths are provided, a soft 
magnetic layer 20, a non-magnetic metal layer 30, a ferromagnetic layer 
40, a pinning layer 50, a ferromagnetic layer 40, a non-magnetic metal 
layer 30, a soft magnetic layer 20, a non-magnetic metal layer 30, a 
ferromagnetic layer 40, a pinning layer 50, a ferromagnetic layer 40, a 
non-magnetic metal layer 30, a soft magnetic layer 20 and a protection 
layer 80 are successively laminated in this order on the metal undercoat 
layer 10 on the substrate 5. When four paths are provided, on the metal 
undercoat layer 10 on the substrate 5 are successively laminated a soft 
magnetic layer 20, a non-magnetic metal layer 30, a ferromagnetic layer 
40, a pinning layer 50, a ferromagnetic layer 40, a non-magnetic metal 
layer 30, a soft magnetic layer 20, a non-magnetic metal layer 30, a 
ferromagnetic layer 40, a pinning layer 50, a ferromagnetic layer 40, a 
non-magnetic metal layer 30, a soft magnetic layer 20, anon-magnetic metal 
layer 30, a ferromagnetic layer 40, a pinning layer 50, a ferromagnetic 
layer 40, a non-magnetic metal layer 30, a soft magnetic layer 20 and a 
protection layer 80 in this order. When ten or more paths are provided, 
the thickness of the whole magnetic multilayer film is large, so that it 
is not applicable to the MR head or the like for ultrahigh density 
magnetic recording. The number of the paths may be equal to one, however, 
it should be set to two or more to obtain a larger MR effect. Practically, 
it is preferably set to 2 to 5. 
As described above, both the whole end portions 200a, 200a of the 
magnetoresistance effect element 200 are contacted with the electrode 
portions 100. Therefore, all the electrons intensively and equivalently 
flow into the two or more portions which are sandwiched between the soft 
magnetic layer 20 and the ferromagnetic layer 40. Accordingly, the rate of 
the electrons which are magnetically scattered by the direction of the 
spins of the soft magnetic layer 20 and the ferromagnetic layer 40 is more 
increased as compared with the case where one path is provided, so that 
the magnetoresistance change is enhanced. Accordingly, a fine change of 
external magnetic field can be detected as a large change of electrical 
resistance. Furthermore, the pinning layer 50 has a large resistivity of 
100 .mu..OMEGA.cm or more, so that the resistivity of the whole magnetic 
multilayer film serving as the magnetically-sensitive portion is 
increased. It is 3 to 10 times as high as the conventional material, NiFe 
(permalloy), however, by forming a number of current-flowing paths as 
described above, the resistivity can be reduced to the same degree as 
permalloy. As a result, temperature rise-up in the magnetically-sensitive 
portion due to flow of a measurement current and deterioration in 
characteristics caused by the temperature rise-up can be avoided. 
Furthermore, as described above, in a case where two or more 
electron-flowing paths are formed with the pinning layer 50 serving as the 
boundary, the balance between the layer thickness and the scattering 
efficiency becomes best when the thickness of each layer is adjusted to 
satisfy the following equation: 
EQU 0.3 Ms.ltoreq.Mf.ltoreq.0.8 Ms, preferably 0.4 Ms.ltoreq.Mf.ltoreq.0.7 Ms, 
where the magnetization of the ferromagnetic layer is represented by Mf and 
the magnetization of the soft magnetic layer is represented by Ms. 
The material and thickness of each layer of the magnetoresistance effect 
element 200 serving as the magnetically-sensitive portion of the second MR 
head is identical to those of the magnetoresistance effect element 4 
having the magnetic multilayer film as described above. 
As described above, at least at the film formation time of the soft 
magnetic layer 20, the external magnetic field is applied in one direction 
within the film plane to induce anisotropic magnetic field Hk, thereby 
making the high-frequency characteristic excellent. Here, the external 
magnetic field is applied in such a direction that a electric current 
flows to induce the MR effect in the magnetic multilayer, thereby inducing 
the anisotropic magnetic field. Usually, the magnetic multilayer film is 
processed in a strip form, and the electric current is controlled to flow 
along the longitudinal direction of the magnetic multilayer film. 
Therefore, it is best to perform the film formation while applying the 
magnetic field in the longitudinal direction. In other words, it is 
preferable that the film formation is performed while the magnetic field 
is applied in the same direction as the electric current flow of the MR 
head, that is, in a direction which is perpendicular to the signal 
magnetic field direction and is an in-plane direction. Accordingly, in the 
soft magnetic layer constituting the magnetic multilayer film in the shape 
of the strip, the longitudinal direction thereof becomes a 
magnetization-easy direction, and the short-side direction thereof becomes 
a magnetization-hard direction, so that anisotropic magnetic field Hk 
occurs. In this case, since the signal magnetic field is applied in the 
short-side direction of the magnetic multilayer film in the shape of the 
strip, the high-frequency magnetic characteristic of the soft magnetic 
layer is improved, and the large MR characteristic in a high frequency 
area can be obtained. It is preferable that the magnitude of the applied 
magnetic field is in the range of 10 to 300 Oe. The anisotropic magnetic 
field Hk which is induced in the soft magnetic layer 20 is in the range of 
3 to 20 Oe, preferably 3 to 16 Oe, more preferably 3 to 12 Oe. If the 
anisotropic magnetic field Hk is lower than 3 Oe, it is equal to the same 
degree as the coercive force of the soft magnetic layer 20, so that no 
linear MR change curve can be substantially obtained in the vicinity of 
the zero magnetic field. Therefore, the characteristic as the MR head is 
deteriorated. On the other hand, if the anisotropic magnetic field Hk is 
higher than 20 Oe, the MR slope (MR ratio per unit magnetic field) is 
reduced, so that the output is liable to be reduced and the resolution is 
reduced when it is used as the MR head or the like. The film of the 
present invention exhibits high heat resistance, and its MR slope at the 
rise-up portion of the MR change curve is above 0.3%/Oe or more, 
particularly 0.4%/Oe or more, usually 0.4 to 1.0%/Oe. The maximum 
hysteresis width of the MR change curve is equal to 8 Oe or less, usually 
0 to 6 Oe. In addition, the MR slope at the high-frequency magnetic field 
of 1 MHz can be equal to 0.2%/Oe or more, preferably 0.25 0%/Oe or more, 
usually 0.3 to 1.0%/Oe. Therefore, sufficient performance can be obtained 
as the reading MR head or the like for the high density recording. 
Furthermore, when an antiferromagnetic layer is formed as the pinning layer 
50, the magnetic field is preferably applied in a direction perpendicular 
to the direction of the magnetic field applied at the film formation time 
of the soft magnetic film 20. That is, it is applied within the film plane 
of the magnetic multilayer film and in a direction vertical to the 
measurement direction. The magnitude of the applied magnetic field is 
preferably set in the range of 10 to 300 Oe. With this operation, the 
magnetization direction of the ferromagnetic layer 40 is surely fixed in 
the applied magnetic field direction (the direction perpendicular to the 
measurement current) by the pinning layer 50, whereby the magnetization of 
the ferromagnetic layer can be most reasonably set to be in antiparallel 
to the magnetization of the soft magnetic layer 20 whose direction can be 
freely changed by the signal magnetic field. However, this is not a 
necessary condition, and the direction of the magnetic field to be applied 
at the film formation time of the antiferromagnetic layer may be 
coincident with the direction of the magnetization of the magnetic field 
to be applied at the film formation time of the soft magnetic layer. At 
this time, it is preferable that the temperature is decreased while 
applying the magnetic field in a stripe short-side direction (a direction 
perpendicular to the direction of the applied magnetic field when the soft 
magnetic layer 20 is formed), when the heat treatment at about 200.degree. 
C. is carried out in the process after the magnetic multilayer film is 
formed. 
The rise-up portion of the MR curve is determined by the rotation of the 
magnetization of the soft magnetic layer 20. In order to obtain a sharper 
rise-up of the MR curve, it is preferable that the magnetization direction 
of the soft magnetic layer 20 is perfectly varied due to the magnetization 
rotation in accordance with the signal magnetic field. However, actually, 
magnetic domains occur in the soft magnetic layer 20, and a movement of 
domain wall and a magnetization rotation occur simultaneously, so that 
Barkhausen noises are produced and thus the MR head characteristic is not 
stabilized. 
Accordingly, as a result of inventor's earnest studies, it has been found 
out that the noises can be reduced by interposing a linking soft magnetic 
layer 500 between the magnetoresistance effect element 200 and each of the 
electrode portions 100 through which the measurement current flows. Of 
course, in this case, the linking soft magnetic layers 500 are connected 
to the magnetoresistance effect element 200 in contact with the whole end 
portions 200a, 200a. The linking soft magnetic layers 500, 500 which are 
formed adjacently to the magnetoresistance effect element (magnetic 
multilayer film) are magnetically directly contacted with the soft 
magnetic layer constituting the magnetic multilayer film. The added 
linking soft magnetic layer 500 has an effect of approaching the magnetic 
domains of the soft magnetic layer in the magnetic multilayer film to a 
magnetic monodomain structure and stabilize the magnetic domain structure. 
As a result, the soft magnetic layer in the magnetic multilayer film acts 
in a magnetization rotation mode to the signal magnetic field, and an 
excellent characteristic having no noise can be obtained. 
In order to make approaching the magnetic domains of the soft magnetic 
layer in the magnetic multilayer film to the magnetic monodomain and 
stabilize the magnetic domain structure, linking soft magnetic layers 510, 
510 having such a shape as shown in FIG. 7 are preferably provided. The 
linking soft magnetic layers 510 are formed not only between the 
magnetoresistance effect element 200 serving as the magnetically-sensitive 
portion and the electrode portions 100, but also on the lower surfaces 101 
of the electrode portions 100 continuously. This is because the degree of 
stabilization is larger as the volume of the linking soft magnetic layer 
510 to stabilize the magnetic domain structure increases. In addition, if 
it is directly contacted with the electrode portion 100, there occurs no 
voltage effect, and it is favorable because the MR effect of the 
magnetic-domain stabilizing linking soft magnetic layer itself has no 
effect on the MR effect of the magnetic multilayer film. Furthermore, in 
order to further positively stabilize the magnetic domains of the soft 
magnetic layer in the magnetic multilayer film, an antiferromagnetic layer 
may be interposed between the electrode portions 100 and the linking soft 
magnetic layers to stabilize the magnetic domain structure. 
In general, in an MR head using permalloy, a shunt layer formed of Ti or 
the like and a bias magnetic-field applying layer of soft magnetic 
material having high resistivity such as CoZrMo, NiFeRh or the like, are 
usually provided adjacently to the magnetically-sensitive portion. These 
are called as soft film bias or shunt bias, and act to shift the curve of 
permalloy and produce a linear area in the vicinity of the zero magnetic 
field. However, the mechanism of this phenomenon is complicated, and it is 
actually a factor of greatly reducing the manufacturing yield. On the 
other hand, in the magnetoresistance effect element (magnetic multilayer 
film) of the present invention as described above, the MR curve rises up 
just in the vicinity of the zero magnetic field, so that a linear area can 
be produced in the vicinity of the zero magnetic field by a self-bias 
which is caused by electric current flowing in the magnetoresistance 
effect element (magnetic multilayer film). As a result, a biasing means 
having a complicated mechanism is not required, so that the manufacturing 
yield can be improved, the manufacturing time can be shortened and the 
cost can be reduced. Furthermore, the thickness of the 
magnetically-sensitive portion is thinner because no biasing mechanism is 
required, so that the shield thickness is made thin when it is used as the 
MR head, and it is greatly effective to shorten the wavelength of signals 
for the ultrahigh density recording. 
When these MR heads are manufactured, heat treatments such as baking, 
annealing, resist curing, etc. are indispensable for a patterning process, 
a flattening process, etc. in the manufacturing process. 
In general, a problem of heat-resistance frequently occurs in the 
magnetoresistance effect element having the magnetic multilayer film, 
which is called as superlattices, due to the thickness of each layer. 
According to the magnetoresistance effect element(magnetic multilayer 
film) of the present invention, the magnetic field is applied to provide 
anisotropic magnetic field in the magnetic layer, so that it can endure a 
heat treatment at a temperature below 500.degree. C. or less, generally 
50.degree. to 400.degree. C., 100.degree. to 300.degree. C. for about two 
hours. The heat treatment is generally performed under vacuum, inert gas 
atmosphere, or atmospheric air. Particularly, if the heat treatment is 
conducted under a vacuum (pressure-reduced) state below 10.sup.-7 Torr or 
less, a magnetoresistance effect element (magnetic multilayer) whose 
characteristic is extremely less deteriorated can be obtained. 
Furthermore, the MR characteristic is little deteriorated even by a 
lapping or a polishing in a processing process. 
The invention of the first and second magnetoresistance effect elements and 
the invention of the first and second magnetoresistance devices (for 
example, MR head) will be described in more detail using the following 
examples . First, an example of the invention of the magnetoresistance 
effect element 3 having the magnetic multilayer film 1 (corresponding to 
FIG. 1) is first described as an example 1. 
EXAMPLE 1 
A glass substrate was used as the substrate. The glass substrate was placed 
in an ion-beam sputtering device, and evacuated until 1.times.10.sup.-7 
Torr. The substrate was cooled and kept at 10.degree. C., and an 
artificial lattice magnetic multilayer film having the following 
composition was formed on the substrate being rotated at 20 r.p.m. At this 
time, the film formation was carried out at a film growth rate of about 
0.3 .ANG./second or less while a magnetic field was applied in a direction 
of a parallel to a measurement electric current and in an in-plane 
direction. Ar flow rate was set to 8 to 10 SCCM, an acceleration voltage 
of a sputter gun was set to 300V and an ion electric current was set to 30 
mA. After the film formation, the resultant was cooled from 150.degree. C. 
under a pressure of 10.sup.-5 Torr while a magnetic field of 200 Oe was 
applied in a direction of a vertical to the measurement electric current 
and in the in-plane direction, thereby a pinning effect in the 
ferromagnetic layer was induced. Samples 1 to 11 shown in table 1 were 
prepared in the manner as described above. 
In table 1, sample 1 was formed of Ni.sub.0.81 Fe.sub.0.19 
(70)-Cu(30)-Ni.sub.0.81 Fe.sub.0.19 (70)-Fe.sub.0.5 Mn.sub.0.5 (70)!, and 
it was a magnetic multilayer film obtained by successively sputtering a 70 
.ANG.-thickness soft magnetic layer of permalloy alloy composition (NiFe) 
containing Ni81%-Fe19%, a 30 .ANG.-thickness non-magnetic metal layer of 
Cu, a 70 .ANG.-thickness ferromagnetic layer of NiFe, and a 70 
.ANG.-thickness antiferromagnetic layer of FeMn alloy containing 
Fe50%-Mn50%. The materials of the soft magnetic layer, the non-magnetic 
metal layer, the ferromagnetic layer and the pinning layer of each sample 
are represented by (m1, m2, m3, m4) in this order. The thickness of the 
respective layers is represented by (t1, t2, t3, t4) in this order in 
table 1. Each sample was provided with Ta layers of 50 .ANG. as the 
undercoat layer (between the substrate and the soft magnetic layer) and 
the protection layer (on the antiferromagnetic layer). 
For the material m1 in the table 1, NiFe (samples 1, 2, 3, 10 to 13, 15, 
17) represents Ni.sub.0.81 Fe.sub.0.19 (weight ratio), CoFeNiB (samples 4, 
7) represents (Co.sub.0.88 Fe.sub.0.06 Si.sub.0.06).sub.0.80 B.sub.0.20 
(atomic ratio), NiFeCo (samples 5, 9) represents Ni.sub.0.17 Fe.sub.0.35 
Co.sub.0.48 (weight ratio), and NiFeCo (samples 6, 8) represents 
Ni.sub.0.15 Fe.sub.0.69 Co.sub.0.16 (weight ratio). 
For the material m4 in the table 1, the samples 1, 2, 4 to 7 are examples 
of the antiferromagnetic layer, the samples 8, 9 are examples of the hard 
magnetic layer, the samples 3 and 10 are examples of ferromagnetic layers 
of different materials, and the sample 11 is an example of a structural 
defect introduced layer, that is, an example in which this layer was 
formed while introducing structural defects at the film formation time of 
Fe.sub.30 Tb.sub.70. Furthermore, for the material m4 in the table 1, CoPt 
of the sample 8 represents Co.sub.0.14 Pt.sub.0.86 (atomic ratio), CoSm of 
the sample 9 represents Co.sub.0.63 Sm.sub.0.37 (atomic ratio), CoFe of 
the sample 3 represents Co.sub.0.81 Fe.sub.0.19, and CoFeNi of the sample 
10 represents Co.sub.0.72 Fe.sub.0.13 Ni.sub.0.15. 
Next, characteristic estimation which is common in the respective 
inventions will be described hereunder. A B-H loop was measured by means 
of a vibrating sample magnetometer (VSM). A measurement of resistance was 
performed as follows. Samples having a shape of 0.5.times.10 mm were 
prepared from the samples having the compositions shown in the table 1, 
and the resistance of each sample was measured by a four-terminal method 
in which an external magnetic field was applied to the sample in the 
in-plane direction and in a direction of a perpendicular to the electric 
current while the external magnetic field was varied from -300 to 300 Oe. 
On the basis of the measured resistance, the minimum value of the 
resistivity .rho..sub.sat and the MR ratio .DELTA.R/R were calculated. The 
MR ratio .DELTA.R/R was calculated according the following equation: 
EQU .DELTA.R/R=(.rho..sub.max -.rho..sub.sat).times.100/.rho..sub.sat (%), 
where the maximum resistivity is represented .rho..sub.max and the minimum 
resistivity is represented by .rho..sub.sat. Furthermore, the differential 
curve was obtained from a measured MR curve, and with respect to the 
rise-up characteristic, the maximum value in the vicinity of the zero 
magnetic field was estimated as the MR slope (unit %/Oe). This value is 
required to be 0.3%/Oe or more as described above. 
The sample 1 has NiFe (permalloy) for the two magnetic layers. It has an MR 
ratio of 1.8%, and a large MR slope of 0.57%/Oe. FIG. 8 is a graph showing 
an MR curve measured under a DC magnetic field, and it shows the output 
voltage at a measurement electric current of 5 mA. The MR curve sharply 
rises up in the vicinity of the zero magnetic field, and it has a large MR 
slope. In the sample 2, the ferromagnetic layer of Co was formed, and in 
the sample 3, the pinning layer was formed by direct exchange-coupling 
with a ferromagnetic layer having different material. In the sample 3, 
before the FeCo layer was deposited in a manner of the sputtering, the Co 
layer was irradiated with an assist ion beam under the following condition 
to roughen the interface portion,: Ar flow rate of 10 SCCM, ion gun 
acceleration voltage of 100V and ion electric current of 10 mA, whereby 
artificial structural defects were introduced. 
Furthermore,in the samples 1 to 11 as shown in the table 1, each section of 
samples was observed by using X-ray diffraction and a transmission 
electron microscope. As a result, it was confirmed that the lattice 
fringes of the respective ferromagnetic layer and the so-called pinning 
layer were linked to each other and thus both the layers were formed by 
the epitaxial growth. 
The sample 12 (comparative example) shown in the table 1 had the same 
multilayer structure as the sample 1, however, in this sample, the 
ferromagnetic layer and the so-called pinning layer were not formed by the 
epitaxial growth due to the difference of a film forming condition 
therebetween. The specific film forming condition of the sample 12 
(comparative example) was set to Ar flow rate of 10 to 20 SCCM, sputtering 
gun acceleration voltage of 1200V and ion electric current of 120 mA, and 
the other condition was identical to the film formation condition as 
described above. Under such a film forming condition, the energy of 
sputtering beams is large, and thus particles which are sputtered from a 
target onto a substrate also have large kinetic energy. Therefore, the 
respective layer materials are mutually diffused into each other at the 
interfaces of the magnetic multilayer film, and no film based on the 
epitaxial growth can be obtained. 
In each of the sample 13 (comparative example) and 14 (comparative 
example), no pinning layer (corresponding to m4) was formed. 
The sample 15 (comparative example) had the same multilayer structure as 
the sample 1, however, in this sample the ferromagnetic layer and the 
so-called pinning layer were not formed by the epitaxial growth due to the 
difference of the film forming condition therebetween. That is, in the 
sample 15 (comparative example), the film formation was performed by an RF 
sputtering method. The ultimate pressure was set to 6.times.10.sup.-7 Torr 
and the pressure at the film formation time was set to 0.5 mTorr. The Ar 
flow rate was set to 8 to 20 SCCM. The section of the multilayer film was 
observed by a high-resolution transmission electron microscope (TEM), and 
as a result no crystal lattice fringe between the pinning layer and the 
ferromagnetic layer was observed. Accordingly, no epitaxial growth state 
existed between these layers. 
The sample 16 (comparative example) had the same multilayer structure as 
the sample 8, however, in this sample the ferromagnetic layer and the 
pinning layer were not formed by the epitaxial growth due to the 
difference of the film forming condition therebetween. The sample 16 
(comparative example) was formed by the same film forming method as the 
sample 15 (comparative example). 
The sample 17 (comparative example) had the same multilayer structure as 
the sample 10, however, in this sample the ferromagnetic layer and the 
so-called pinning layer were not formed by the epitaxial growth due to the 
difference of the film forming condition therebetween. The sample 17 
(comparative example) was formed by the same film forming method as the 
sample 15 (comparative example). 
TABLE 1 
__________________________________________________________________________ 
Sample Material Layer thickness 
.rho.sat 
MR ratio 
MR slope 
No. (m1, m2, m3, m4) 
(t1, t2, t3, t4) 
(.mu..OMEGA.cm) 
(%) (%/Oe) 
__________________________________________________________________________ 
1 (NiFe, Cu, NiFe, FeMn) 
(70, 30, 70, 70) 
55.6 
1.8 0.57 
2 (NiFe, Cu, Co, FeMn) 
(70, 35, 60, 70) 
56.3 
2.1 0.52 
3 (NiFe, Cu, Co, CoFe) 
(60, 30, 80, 60) 
45.2 
1.6 0.43 
4 (COFeSiB, Cu, Co, FeMn) 
(80, 25, 40, 120) 
60.5 
3.5 0.48 
5 (NiFeCo, Cu, CoNi, FeMn) 
(70, 35, 60, 100) 
57.2 
3.1 0.41 
6 (NiFeCo, Cu, Co, Fe.sub.2 O.sub.3) 
(80, 30, 60, 500) 
88.6 
4.2 0.78 
7 (CoFeSiB, Cu, CoFe, Fe.sub.2 O.sub.3) 
(80, 30, 60, 300) 
66.9 
5.3 0.72 
8 (NiFeCo, Cu, Co, CoPt) 
(90, 50, 20, 80) 
46.1 
1.7 0.37 
9 (NiFeCo, Cu, Co, CoSm) 
(60, 40, 30, 500) 
75.3 
1.5 0.35 
10 (NiFe, Cu, NiFe, CoFeNi) 
(50, 30, 20, 60) 
42.8 
1.6 0.34 
11 (NiFe, Cu, NiFe, FeTh) 
(60, 30, 80, 200) 
72.3 
2.5 0.37 
12 (compara.) 
(NiFe, Cu, NiFe, FeMn) 
(70, 80, 70, 70) 
65.6 
0.3 0.07 
13 (compara.) 
(NiFe, Cu, NiFe) 
(20, 40, 20) 
28.7 
1.1 0.18 
14 (compara.) 
(Co, Ag, Co) (10, 30, 10) 
18.9 
0.9 0.11 
15 (compara.) 
(NiFe, Cu, NiFe, FeMn) 
(70, 30, 70, 70) 
73.2 
1.1 0.07 
16 (compara.) 
(NiFeCo, Cu, Co, CoPt) 
(90, 50, 20, 80) 
52.8 
0.9 0.16 
17 (compara.) 
(NiFe, Cu, NiFe, CoFeNi) 
(50, 30, 20, 60) 
51.2 
1.6 0.15 
__________________________________________________________________________ 
It is apparent from the result of the table 1 that a large MR slope 
exceeding 0.3%/Oe can be obtained by forming the ferromagnetic layer and 
the so-called pinning layer through epitaxial growth to pin the 
magnetization direction of the ferromagnetic layer (the samples 1 to 11 of 
the present invention). The pinning effect cannot be obtained unless the 
pinning layer and the magnetic layer are formed by the epitaxial growth. 
Furthermore, it is apparent that the pinning effect is achieved by one 
selected from the antiferromagnetic layer, the hard ferromagnetic layer, 
the ferromagnetic layer formed different material and the layer doped with 
the artificial structural defects. 
Next, an example of the invention of the magnetoresistance effect element 4 
having the magnetic multilayer film 2 (corresponding to FIG. 4) will be 
described. 
EXAMPLE 2 
A glass substrate was used as the substrate. The glass substrate was placed 
in an ion-beam sputtering device, and evacuated until 1.times.10.sup.-7 
Torr. The substrate was cooled and kept at 10.degree. C., and an 
artificial lattice magnetic multilayer film having the following 
composition was formed on the substrate which was rotated. At this time, 
the film formation was performed at a film growth rate of about 0.3 
.ANG./second or less, while a magnetic field was applied in a direction of 
a parallel to a measurement electric current and in an in-plane direction. 
Ar flow rate was set to 8 SCCM, an acceleration voltage of sputter gun was 
set to 300V and an ion electric current was set to 30 mA. After the film 
formation, the resultant was cooled from 150.degree. C. under a pressure 
of 10.sup.-7 Torr while a magnetic field of 200 Oe was applied in a 
direction of a vertical to the measurement electric current and in the 
in-plane direction, thereby a pinning effect in the ferromagnetic layer 
was induced. 
The construction of the magnetic multilayer film and the magnetoresistance 
ratio are shown in the following table 2. 
In table 2, sample 2-1 was formed of Ni.sub.0.81 Fe.sub.0.19 
(70)-Cu(30)-Ni.sub.0.81 Fe.sub.0.19 (70)-Fe.sub.0.5 Mn.sub.0.5 
(70)-Ni.sub.0.81 Fe.sub.0.19 (70)-Cu(30)-Ni.sub.0.81 Fe.sub.0.19 (70)!, 
and it was a magnetic multilayer film in which a 70 .ANG.-thickness NiFe 
alloy layer used as a ferromagnetic layer, a 30 .ANG.-thickness 
non-magnetic metal layer of Cu, a 70 .ANG.-thickness soft magnetic layer 
of permalloy composition (NiFe) containing Ni81%-Fe19%, and a 70 
.ANG.-thickness Ta metal layer are successively laminated on each of both 
sides of a 70 .ANG.-thickness antiferromagnetic layer (pinning layer) of 
FeMn alloy containing Fe50%-Mn50%. The materials of the soft magnetic 
layer, the non-magnetic metal layer, the ferromagnetic layer and the 
antiferromagnetic layer (pinning layer) constituting each sample are 
represented by (m1, m2, m3, m4) in this order. The thickness of the 
respective layers is represented by (t1, t2, t3, t4) in this order in 
table 2. In the following examples, each composition of NiFe and FeMn 
layers is identical to that of the example 1. The MR slope under the DC 
magnetic field and the MR slope (unit %/Oe) at 6 Oe width under 
high-frequency magnetic field of 1 MHz are shown, respectively. As 
described above, this value is required to be 0.2%/Oe or more. In 
addition, the value of Mf/Ms is also shown, where the magnetization of the 
ferromagnetic layer is represented by Mf and the magnetization of the soft 
magnetic layer is represented by Ms. The thickness of each layer is 
selected so that the above value(Mf/Ms) is equal to 0.3 to 0.8. 
TABLE 2 
__________________________________________________________________________ 
Sample Material Layer thickness 
.rho.sat 
MR ratio 
MR slope 
High frequency 
No. (m1, m2, w3, w4) 
(t1, t2, t3, t4) 
(.mu..OMEGA.cm) 
(%) (%/Oe) 
MR slope (%/Oe) 
Mf/Ms 
__________________________________________________________________________ 
2-1 (NiFe, Cu, NiFe, FeMn) 
(70, 30, 40, 70) 
37.6 
2.8 0.75 0.60 0.57 
2-2 (NiFe, Cu, Co, FeMn) 
(80, 35, 40, 70) 
36.3 
2.9 0.71 0.52 0.67 
2-3 (NiFe, Cu, Co, FeCo) 
(60, 80, 80, 60) 
31.4 
1.8 0.51 0.46 0.67 
2-4 (NiFe, Cu, Co) 
(50, 50, 50) 
17.0 
5.6 0.53 0.49 -- 
1 (NiFe, Cu, NiFe, FeMn) 
(70, 30, 70, 70) 
55.6 
1.8 0.57 0.26 1.00 
2 (NiFe, Cu, Co, FeMn) 
(70, 35, 60, 70) 
56.3 
2.1 0.52 0.27 1.14 
2-5 (compara.) 
* 47.0 
0.8 0.38 0.20 -- 
__________________________________________________________________________ 
*: NiFe (70A) Cu (30A)NiFe (70A)FeMn (70A)Cu (30A)NiFe (70A)Cu (30A)NiFe 
(70A)FeMn (70A)Cu (50A) 
The samples 2-1 to 2-4 shown in the table 2, have the structure of the 
magnetoresistance effect element 4 having the magnetic multilayer film 2 
(corresponding to FIG. 4), and the samples 1 and 2 shown in table 2 are 
identical to the samples 1 and 2 of the table 1, where one soft magnetic 
layer and one antiferromagnetic layer are provided (corresponding to FIG. 
1). Each section of the laminate film samples was observed with X-ray 
diffraction and the transmission electron microscope, and it was confirmed 
that the lamination of the ferromagnetic layer and the pinning layer in 
the samples 2-1 to 2-4 and the samples 1 and 2 were formed by the 
epitaxial growth. 
In the sample 2-5 (comparative example), Ta(50 .ANG.) was formed as an 
undercoat layer on the substrate, and then NiFe(70 .ANG.), Cu(30 .ANG.), 
NiFe(70 .ANG.), FeMn(70 .ANG.), Cu(30 .ANG.), NiFe(70 .ANG.), Cu(30 
.ANG.), NiFe(70 .ANG.), FeMn(70 .ANG.) and Cu(30 .ANG.) were successively 
formed on the undercoat layer in this order. The film was formed as the 
same condition as that of the sample 12. As a result, it was confirmed for 
the sample 2-5 (comparative example) that the ferromagnetic layer and the 
so-called pinning layer were not coupled to each other with the epitaxial 
growth. 
The magnetization curve and the MR curve of the sample 2-1 in the table 2 
are shown in FIGS. 9(A) and (B), respectively. As described later, the 
magnetization curve of the sample 1 of the table 1 (identical to the 
sample 1 of the table 2) is shown in FIGS. 10(A) and (B). 
By comparing these curves, it is found that the magnetoresistance effect 
element 4 having the magnetic multilayer film 2 according to the present 
invention has a larger MR slope at the rise-up portion of the MR curve, 
and thus the magnetic field shift amount Hex due to the exchange-coupling 
between the antiferromagnetic layer and the ferromagnetic layer is larger. 
Furthermore, from the result of the table 2, it is found out that by 
laminating the ferromagnetic layer, the non-magnetic metal layer and the 
soft magnetic layer in this order on each of both sides of the pinning 
layer, and particularly by coupling the pinning layer and the 
ferromagnetic layers at both side of the pinning layer with the epitaxial 
growth, not only the MR ration and the MR slope under the DC magnetic 
field, but also the high-frequency MR characteristic which is most 
important for practical use and represented by the MR slope at 1 MHz can 
be greatly improved. With this structure, particularly only the samples 
2-1 to 2-4 exhibit a large high-frequency MR slope exceeding 0.3%/Oe. 
Furthermore, it is found out that on condition of 
0.3.ltoreq.Mf/Ms.ltoreq.0.8 (Mf: magnetization of the ferromagnetic layer, 
Ms: magnetization of the soft magnetic layer), an excellent high-frequency 
MR characteristic can be obtained. 
Further, the sample 1 of the table 1 and the sample 2-1 of the table 2 were 
subjected to the heat treatment at 230.degree. C. for 4 hours under a 
vacuum state of 10.sup.-5 Torr. .rho..sub.sat, MR ratio, MR slope under DC 
magnetic field and high-frequency MR slope after the heat treatment are 
shown in table 3. 
TABLE 3 
______________________________________ 
Sample .rho.sat 
MR ratio MR slope 
High frequency 
No. (.mu..OMEGA.cm) 
(%) (%/Oe) MR slope (%/Oe) 
______________________________________ 
1 54.2 1.9 0.59 0.24 
2-1 39.1 2.7 0.72 0.58 
______________________________________ 
From the result of the table 3, there occurred little deterioration in 
characteristics both at the initial stage and after the heat treatment. 
That is, the magnetoresistance effect element 4 having the magnetic 
multilayer film 2 exhibits a large MR slope which exceeds 0.3%/Oe under a 
large DC magnetic field, and a large high-frequency MR slope at 1 MHz. 
FIGS. 10(A) and (C) show the magnetization curves of the magnetic 
multilayer film constituting the sample 1 of the table 1 just after the 
film formation is performed and after the heat treatment is performed, 
respectively. FIGS. 10(B) and (D) show the MR curves of the magnetic 
multilayer film constituting the sample 1 of the table 1 just after the 
film formation is performed and after the heat treatment is performed, 
respectively. FIGS. 11(A) and (C) show the magnetization curves of the 
magnetic multilayer film constituting the sample 2-1 of the table 2 just 
after the film formation is performed and after the heat treatment is 
performed, respectively. FIGS. 11(B) and (D) show the MR curves of the 
magnetic multilayer film constituting the sample 2-1 of the table 2 just 
after the film formation is performed and after the heat treatment is 
performed, respectively. In the sample 2-1, the intensity of the 
exchange-coupling force is different between the upper and lower portions 
of the antiferromagnetic layer (pinning layer), so that Hex is also 
different between the upper and lower soft magnetic layers after the heat 
treatment. However, both the samples have little variation of the rise-up 
portion of the MR curve in the vicinity of the zero magnetic field, which 
is practically important, and the excellent MR characteristic of the 
magnetization curve can be kept both just after the film formation is 
performed and after the heat treatment. FIGS. 12(A) and (B) show the X-ray 
diffraction curves of the sample 2-2 of the table 2 just after the film 
formation is performed and after the heat treatment. The diffraction 
intensity of a (111)-orientation plane from the NiFe and Co layers at the 
angle of about 44 degrees is slightly higher after the heat treatment than 
just after the film formation, however, there is substantially little 
variation. 
Furthermore, FIG. 13 shows variation of the MR slope when the sample 2-1 of 
the table 2 is thermally treated under various pressure values. At 
250.degree. C., little variation occurs in the MR slope under any 
pressure. However, at 350.degree. C., some variation occurs in accordance 
with the applied pressure. That is, the MR slope keeps a large value for 
the heat treatment in a pressure range lower than 10.sup.-7 Torr, however, 
the MR slope is deteriorated in a pressure range higher than 10.sup.-7 
Torr. This is because the magnetic multilayer film is oxidized by a slight 
amount of residual oxygen although it is called as a vacuum state. 
However, at 450.degree. C., the MR slope is also deteriorated under a 
pressure of 10.sup.-9 Torr. Accordingly, it is understood that the MR 
slope keeps a large value in the heat treatment of the temperature below 
400.degree. C. and of the pressure of lower than 10.sup.-7 Torr. 
Furthermore, in the invention of the magnetoresistance effect element 4 
having the magnetic multilayer film 2 (corresponding to FIG. 4), was 
performed an experiment of examining what effects are brought to the 
characteristics of the multilayer film by the relationship among the 
resistivity .rho..sub.p of the pinning layer, the resistivity .rho..sub.f 
of the ferromagnetic layer and the resistivity .rho..sub.s of the soft 
magnetic layer. That is, magnetic multilayer films responding to FIG. 4) 
having various laminate compositions as shown in the following table 4 
were prepared, and the resistivity of each layer, .rho..sub.p, 
.rho..sub.f, .rho..sub.s and the value R*=.rho..sub.p /(.rho..sub.s 
+.rho..sub.f)/2! were calculated. In addition, the MR value and the MR 
slope for each sample was measured. The result is shown in the following 
table 4. The value R*=.rho..sub.p /(.rho..sub.s +.rho..sub.f)/2! was 
found out to be excellent in a range of 3 to 30, that is, the samples 4-1 
to 4-4 satisfying the following equation (1) exhibit excellent results. 
EQU 3((.rho..sub.f +.rho..sub.s)/2)&lt;.rho..sub.p &lt;30((.rho..sub.f 
+.rho..sub.s)/2) equation (1) 
TABLE 4 
__________________________________________________________________________ 
Sample 
Material .rho..sub.f 
MR ratio 
MR slope 
No. (m.sub.s, m.sub.f, m.sub.p) 
.rho..sub.s 
(.mu..OMEGA.cm) 
.rho..sub.p 
R* (%) (%/Oe) 
__________________________________________________________________________ 
4-1 (NiFe, NiFe, FeMn) 
27.3 
27.3 
124 
4.5 
1.8 0.57 
4-2 (NiFeCo, Co, FeMn) 
28.8 
24.6 
124 
4.6 
3.5 0.60 
4-3 (CoNiFe, CoFe, FeCoMn) 
24.7 
29.6 
147 
5.4 
3.8 0.56 
4-4 (NiFe, Co, CrSb) 
27.3 
24.6 
358 
13.8 
2.1 0.54 
4-5 (NiFe, NiFe, CoPt) 
27.3 
27.3 
34.1 
1.2 
1.7 0.37 
4-6 (NiFe, Co, CoFe) 
27.3 
24.6 
29.6 
1.1 
1.6 0.41 
__________________________________________________________________________ 
m.sub.s : matetial of soft magnetic layer 
m.sub.f : matetial of ferromagnetic layer 
m.sub.p : matetial of pinning layer 
R* = .rho..sub.p /(.rho..sub.s + .rho..sub.f)/2 
Next, in order to consider the laminating order of the respective layers of 
the magnetoresistance effect element having the magnetic multilayer film 2 
(corresponding to FIG. 4) of the invention, a magnetic multilayer film of 
a comparative sample 5-1 whose laminating order was different from that of 
the magnetic multilayer film 2 (corresponding to FIG. 4 of the present 
invention was prepared. That is, the magnetic multilayer film of the 
comparative sample 5-1 was formed by successively laminating, on a Ta 
undercoat layer (50 .ANG.), NiFe(70 .ANG.)/Cu(30 .ANG.)/NiFe(70 
.ANG.)/FeMn(70 .ANG.)/Cu(30 .ANG.)/NiFe(70 .ANG.)/Cu(30 .ANG.)/NiFe(70 
.ANG.)/FeMn(70 .ANG.)/Cu(50 .ANG.). This film was obtained by using the 
magnetic multilayer film 1 shown in FIG. 1 as a basic unit and stacking 
the basic units in the same laminating order so that Cu(30 .ANG.) was 
sandwiched between the two basic units. The MR curve of the comparative 
sample 5-1 is shown in FIG. 18. From the graph of FIG. 18, the comparative 
sample 5-1 has an extremely small MR ratio as indicated on the ordinate, 
and a MR ratio curve in which an applied magnetic field is increased and a 
MR ratio curve in which an applied magnetic field is decreased, are not 
coincident with each other in the vicinity of the zero magnetic field, so 
that this sample was found to be unusable practically. This shows that 
even if the layers are successively laminated from the Ta undercoat layer 
side and the NiFe layer serving as the first ferromagnetic layer and even 
if the FeMn layer serving as the pinning layer are coupled to each other 
with the epitaxial growth, the epitaxial growth is gradually lost as the 
lamination further proceeds in the order of Cu, NiFe and Cu again, and 
finally the epitaxial relationship cannot be obtained between subsequent 
NiFe-FeMn layers. Accordingly, in order to pin the ferromagnetic layer 
most efficiently, it is best that the ferromagnetic layers are formed at 
the upper and lower sides of the pinning layer like the magnetic 
multilayer film 2 of the present invention(corresponding to FIG. 4), and 
these layers are epitaxially formed. 
Further, the following examples 3 to 6 and a comparative example 1 will be 
described as the invention of the first MR head as a magnetoresistance 
device and a comparative example. 
EXAMPLE 3 
Ta of 50 .ANG. thickness was formed as a metal undercoat layer on an AlTiC 
substrate, and NiFe(70 .ANG.)-Cu(30 .ANG.)-NiFe(70 .ANG.)-FeMn(70 .ANG.) 
were successively laminated on the metal undercoat layer to form a 
magnetic multilayer film. NiFe represents Ni.sub.0.81 Fe.sub.0.19. The 
film forming condition was as follows: ultimate pressure of 
2.times.10.sup.-7 Torr, pressure of 1.4.times.10.sup.-4 Torr at film 
formation time and substrate temperature of about 10.degree. C., and the 
film formation of each material was performed by the ion beam sputtering 
method at a film growth rate of 0.2 to 0.3 .ANG./sec while a magnetic 
field was applied in a direction of a parallel to a measurement electric 
current and in an in-plane direction during the film formation process. 
The epitaxial growth coupling was confirmed between the NiFe-FeMn layers. 
Thereafter, a pattern of 20 .mu.m.times.6 .mu.m was formed as a 
magnetically-sensitive portion using a photolithographic technique, and an 
electrode having a track width of 3 .mu.m was formed on the pattern to 
form an MR head. The structure of the MR head thus formed is shown in FIG. 
5. Thereafter, it was cooled from 150.degree. C. under a pressure of 
10.sup.-5 Torr while magnetic field of 200 Oe was applied in a direction 
of a perpendicular to the measurement electric current and in the in-plane 
direction, thereby the pinning effect of the ferromagnetic layer was 
induced. FIG. 14 shows variation of the output voltage obtained when the 
measurement electric current was set to 5 mA and the external magnetic 
field was varied in a range of .+-.20 Oe at 50 Hz. According to the MR 
head using the artificial lattice magnetic multilayer film of the present 
invention, the output voltage of about 2.2 mV could be obtained. 
Comparative Example 1 
An MR head utilizing the anisotropic magnetoresistance effect which has 
been hitherto used was prepared as a comparative example with permalloy 
under the same condition as the embodiment 3. The measurement electric 
current was set to 5 mA and the external magnetic field was varied in a 
range of .+-.20 Oe at 50 Hz. The output voltage at this time was equal to 
0.8 mV. 
From the comparison between the example 3 and the comparative example 1, 
the first MR head of the present invention can obtain about three times as 
high as the output of the conventional example. Accordingly, the effect of 
the present invention is clear. 
EXAMPLE 4 
Ta of 50 .ANG. thickness was formed as a metal undercoat layer on an AlTiC 
substrate, and NiFe(70 .ANG.)-Cu(30 .ANG.)NiFe(70 .ANG.)-FeMn(70 
.ANG.)-NiFe(70 .ANG.)-Cu(30 .ANG.)-NiFe(70 .ANG.) were successively 
laminated on the metal backing layer to form a magnetic multilayer film. 
The film forming condition was as follows: ultimate pressure of 
1.7.times.10.sup.-7 Torr, pressure of 1.4.times.10.sup.-4 Torr at film 
formation time and substrate temperature of about 10.degree. C., and the 
film formation of each material was performed by the ion beam sputtering 
method at a film growth rate of 0.2 to 0.3 .ANG./sec while a magnetic 
field was applied in a direction of a parallel to a measurement electrical 
current and in an in-plane direction during the film formation process. 
Thereafter, it was cooled from 150.degree. C. under a pressure of 
10.sup.-5 Torr while magnetic field of 200 Oe was applied in a direction 
of a perpendicular to the measurement electric current and in the in-plane 
direction, thereby the pinning effect of the ferromagnetic layer was 
induced. The other condition was set to be identical to that of the 
example 3, and the MR head was formed. It was confirmed that the 
NiFe--FeMn--NiFe were coupled to one another with the epitaxial growth. 
The structure of the MR head thus formed is shown in FIG. 5. FIG. 15 shows 
variation of the output voltage obtained when the external magnetic field 
was varied in a range of .+-.20 Oe at 50 Hz. According to the MR head 
using the artificial lattice magnetic multilayer film of the present 
invention, the output voltage of about 3.0 mV could be obtained. As 
compared with the example 3, the resistance value between the electrodes 
was reduced by about 30%. This was because the resistivity of the magnetic 
multilayer film was reduced. This is favorable for the operation of the MR 
head because a heating due to the measurement electric current can be more 
suppressed as the resistivity is small. 
In addition, the deterioration of the characteristics of the MR head due to 
the heating can be also suppressed. It was confirmed that the MR head of 
the present invention had about 3.8 times as large as the effect of the 
conventional example. 
EXAMPLE 5 
Furthermore, FIG. 16 shows an embodiment in which the magnetoresistance 
effect element of the present invention is applied to a yoke type MR head. 
In this embodiment, a part of yokes 600, 600 for guiding magnetic flux is 
provided with a cut-out portion, and a magnetoresistance effect element 
200 was formed through a thin insulting film 400 therebetween. The 
magnetoresistance effect element 200 is provided with an electrode (not 
shown) through which a electric current flows in a direction of a parallel 
or perpendicular to the direction of a magnetic path formed by the yokes 
600, 600. As a result, the output which was two times as high as that of 
the MR head using permalloy was obtained. In the magnetic multilayer film 
of the present invention, the rise-up characteristic in the vicinity of 
the zero magnetic field is excellent, and thus a shunt layer and a bias 
magnetic field applying means which are usually used, may not be provided. 
EXAMPLE 6 
FIG. 17 shows another embodiment in which a magnetoresistance device, for 
example, an MR head is constructed by the magnetoresistance effect element 
of the present invention. The magnetoresistance effect element 200 is 
formed in contact with high-resistivity flux guide layers 700, 710 
magnetically. The flux guide layers are formed of material whose 
resistivity is three times or more as high as the resistivity of the 
magnetic multilayer film 200, so that substantially no measurement 
electrical current flowing in the magnetic multilayer film 200, flows in 
the flux guide layers 700, 710. On the other hand, since the flux guide 
layer 700 and the magnetic multilayer film 200 are magnetically contacted 
with each other, the signal magnetic field is guided to the flux guide 
layer 700 and reaches the magnetic multilayer film 200 without losing its 
intensity. Reference numeral 600 represents another different flux guide 
layer, and it acts as a return guide for magnetic flux passing through the 
magnetic multilayer film 200. This flux guide layer 600 may be provided at 
each of both sides of the magnetoresistance effect element 200 and the 
pair of the high-resistivity flux guide layers 700, 710. Furthermore, the 
guide layers 710 and 600 may be contacted with the medium at a far end 
portion. At this time, the output was estimated as being three times as 
large as that of an MR head using permalloy. Reference numeral 400 
represents a non-magnetic insulating layer. 
As described above, according to the first invention on the 
magnetoresistance effect element having the magnetic multilayer film 1, it 
has a MR slope of 0.3%/Oe or more. In addition, the rise-up characteristic 
of the MR curve in the vicinity of the zero magnetic field, is extremely 
excellent, and it has high heat resistance. According to the second 
invention on the magnetoresistance effect element having the magnetic 
multilayer film 2, in addition to the above effects, it has a MR slope at 
a high frequency of 1 MHz of 0.3%;Oe or more, and has a low resistivity. 
Furthermore, the characteristic is not deteriorated even by the heat 
treatment before and after 350.degree. C. insofar as the pressure is below 
10.sup.-7 Torr. In the magnetoresistance device, for example, MR head 
using the magnetoresistance effect element having the magnetic multilayer 
film 1, the output voltage is approximately three times as high as that of 
the conventional material.Furthermore, in the magnetoresistance device, 
for example,MR head using the magnetoresistance effect element having the 
magnetic multilayer film 2, the MR slope in the high-frequency area has a 
high value of 0.3%/Oe or more and a low resistivity, and the heating due 
to the measurement electric current is small, and a 3.8-times output 
voltage can be obtained. Accordingly, there can be provided an excellent 
MR head which has extremely high reliability and enables the reading for 
ultrahigh density magnetic recording which exceeds 1 Gbit/inch.sup.2.