JP2001160640A - Magnetoresistive element, magnetoresistive head, magnetic reproducing device, and magnetic laminate - Google Patents

Abstract

(57) [Summary] An inexpensive and high-performance magnetoresistive element can be provided. Further, a thin-film element can be provided, which is suitable for a magnetic reproducing head requiring a narrow gap and a magnetic reproducing system such as a hard disk drive. An intermediate layer (35) for coupling the magnetization of a ferromagnetic layer in a direction of 90 degrees is inserted between pinned layers (33, 37),
A heat treatment for converting the free layer 41 into a single magnetic domain with the antiferromagnetic material 43 and a heat treatment for fixing the magnetization of the pinned layer are performed simultaneously. Thus, the antiferromagnetic layer 4 in contact with the free layer 41
3 and the blocking temperature of the antiferromagnetic layer 31 in contact with the pinned layer 33 are not required, so that an antiferromagnetic layer having a high exchange coupling magnetic field and a high blocking temperature can be selected. Further, since the allowable range for dispersion of the exchange coupling magnetic field is widened, the antiferromagnetic layer can be made thinner and can be applied to a magnetic reproducing head requiring a narrow gap.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetoresistive element for detecting a change in an external magnetic field, a magnetoresistive head provided with the magnetoresistive element, a magnetic reproducing apparatus equipped with the magnetoresistive head, and a mutual reproducing apparatus. The present invention relates to a magnetic laminate comprising two ferromagnetic layers whose magnetization directions are substantially orthogonal.

[0002]

2. Description of the Related Art Conventionally, to read magnetic information recorded on a magnetic recording medium, a reproducing magnetic head having a coil and a recording medium are relatively moved, and a voltage induced in the coil by electromagnetic induction generated at that time. Has been used. Then, the magnetoresistance effect (MagnetoResista) in which the electrical resistance of a specific ferromagnetic material changes according to the strength of the external magnetic field
(Magnetic resistance effect element (referred to as MR element) that reproduces magnetic information using the
150 (1971) etc.). This MR element is used not only as a magnetic field sensor but also as a magnetoresistive head (MR head) mounted on a magnetic reproducing device such as a hard disk drive.

[0003] The size of a magnetic recording medium mounted on a magnetic reproducing apparatus has been reduced.
In recent years, the increase in capacity has been increasingly advanced, and the relative speed between the reproducing magnetic head and the magnetic recording medium at the time of reading information has become smaller,
There is an increasing expectation for an MR head capable of obtaining a large output even at a small relative speed.

[0004] In response to such expectations, giant magnetoresistive films have been developed. This giant magnetoresistive film is made of Fe /
A multilayered film in which ferromagnetic metal films and non-magnetic metal films such as Cr and Fe / Cu are alternately laminated under predetermined conditions, and adjacent ferromagnetic metal films are antiferromagnetically coupled, a so-called artificial lattice film. (Phys. Rev. Lett. 61 2474 (1988), Phys. Re.
v. Lett. 64 2304 (1990) etc.). However, the artificial lattice film requires a large magnetic field to saturate the magnetization,
Not suitable as film material for head.

On the other hand, in a multilayer film of a ferromagnetic metal layer / a nonmagnetic metal layer / a ferromagnetic metal layer in which a nonmagnetic metal layer is sandwiched between ferromagnetic metal layers from above and below, the two ferromagnetic metal layers are not magnetically coupled (non-magnetic). An example in which a large magnetoresistance effect is realized in an MR film of (bonding) has been reported. This MR film is characterized in that the magnetization (spin) of the ferromagnetic metal layer is fixed, and the magnetization of the other ferromagnetic layer is reversed by an external magnetic field. Thereby, the magnetoresistance effect can be obtained by changing the relative angle of the spin direction of the ferromagnetic metal layer disposed with the nonmagnetic layer interposed therebetween. Such an MR element is called a spin valve element. (Phys. Rev. B 4
5 806 (1992), J. Appl. Phys. 69 4774 (1991), etc.).

Although the spin valve element has a small magnetoresistance change rate as compared with the artificial lattice film, the magnetic field required for saturation of the direct current is small, so that it is suitable for MR head applications and has already been put to practical use. Has reached.

A general spin valve element has a laminated structure of a ferromagnetic free layer, an intermediate nonmagnetic layer, a ferromagnetic pinned layer, and an antiferromagnetic layer. The magnetization of the ferromagnetic pinned layer in contact with the antiferromagnetic layer is fixed in one direction under an external magnetic field by an exchange bias magnetic field from the antiferromagnetic layer. On the other hand, the ferromagnetic free layer can freely rotate with respect to an external magnetic field, and a parallel / anti-parallel state of magnetization of the ferromagnetic free layer and the ferromagnetic pinned layer can be easily realized in a low magnetic field. The electric resistance of the element is low when the magnetizations of both ferromagnetic layers are parallel, and the electric resistance is high when the magnetizations of the two ferromagnetic layers are antiparallel. Is obtained.

When a spin valve element is actually used, the magnetization of the ferromagnetic free layer should be substantially orthogonal to the magnetization of the pinned layer in a zero magnetic field in order to obtain high sensitivity using the linear region of resistance change. Is preferably biased. This bias is also important in terms of forming a single magnetic domain so that Barkhausen noise does not occur when the magnetization of the free layer rotates with respect to an external magnetic field. For this reason, a hard magnetic film having the same function as a magnet is provided on the side surface of the spin valve film for the purpose of forming a single magnetic domain.

When the thickness of the hard magnetic film is equal to the thickness of the ferromagnetic free layer, an appropriate bias can be applied. If the thickness of the hard magnetic film is thinner than this, it is difficult to achieve a single magnetic domain of the ferromagnetic free layer due to insufficient bias. On the other hand, if the thickness is larger than the free layer, the bias becomes excessive and the magnetic permeability of the ferromagnetic free layer decreases.

However, under the present circumstances, if the hard magnetic film is thinned to the same thickness as the ferromagnetic free layer, the junction area between them becomes small, so that the magnetic junction cannot be made well and the hard film is thicker than the ferromagnetic free layer. The configuration has to be taken. As a result, the bias applied to the ferromagnetic free layer becomes excessive, the magnetic permeability of the ferromagnetic free layer decreases, and the sensitivity and the output are lost.

In order to solve this problem, an antiferromagnetic layer having a predetermined shape is laminated at the end of the free layer, and the magnetization at the end of the free layer is fixed by exchange coupling between the antiferromagnetic layer and the free layer. Has proposed a spin valve element having a configuration in which a bias is applied to a central magnetic field response section of a free layer. Since this is a bias method using an antiferromagnetic layer processed into a predetermined shape (pattern), it is called a patterned bias structure.

FIG. 20A is a perspective view of a spin valve element having a patterned bias structure.

This spin valve element has a first antiferromagnetic layer 1, a ferromagnetic pinned layer 3, an intermediate nonmagnetic layer 5, and a ferromagnetic free layer 7, which are stacked in this order from the bottom. 7 has a pair of second antiferromagnetic layers 9 stacked on both ends in the longitudinal direction, and a pair of lead electrodes 11.

Both ends of the ferromagnetic free layer 7 and the ferromagnetic pinned layer 3 are connected to the second antiferromagnetic layer 9 and the first antiferromagnetic layer 1 by magnetic exchange coupling, respectively, as shown in FIG. Unidirectional anisotropic magnetization is provided. That is, the ferromagnetic free layer 7
Of these, the two end portions (hatched portions) stacked with the second antiferromagnetic layer 9 are pinned in the right direction in the drawing by exchange coupling, and act as a hard magnetic film. Then, the magnetization of the central magnetic field responsive portion sandwiched between both ends is subjected to a bias magnetic field from both ends of the second antiferromagnetic layer 9 and the ferromagnetic free layer 7 and is unidirectionally anisotropic in the direction of the arrow at zero magnetic field. Having the magnetization of On the other hand, the magnetization of the ferromagnetic pinned layer 3 is fixed by exchange coupling with the first antiferromagnetic layer 1 in a direction from the front to the back in FIG. 20A.

In the patterned bias structure, the exchange coupling film of the second antiferromagnetic layer 9 and the ferromagnetic free layer 7 and the two exchange coupling films of the first antiferromagnetic layer 1 and the ferromagnetic pinned layer 3 are formed. Required. The unidirectional anisotropy is given to the ferromagnetic layer of the exchange-coupling film by heat treatment in a magnetic field. However, since the magnetization of the ferromagnetic pinned layer 3 and the magnetization of the ferromagnetic free layer 7 influenced by each need to be orthogonal, Heat treatment must be performed in a state where different magnetic fields are applied to the antiferromagnetic layers 1 and 9 respectively. The blocking temperature of the first antiferromagnetic layer 1 at which the exchange coupling magnetic field with the ferromagnetic pinned layer 3 becomes zero is T _B1 , and the blocking of the second antiferromagnetic layer 9 at which the exchange coupling magnetic field with the ferromagnetic free layer becomes zero. heat treatment process when the temperature was T _B2 (time - temperature) are shown in Figure 20 (b). Since the antiferromagnetic film has uniaxial anisotropy, its magnetization state is indicated by a bidirectional arrow for convenience.

In order to completely fix the magnetization by the first and second antiferromagnetic layers 1 and 9, the difference in blocking temperature | Tb
Two kinds of antiferromagnetic layer materials having a large ₁₋ Tb ₂ | are required, and further, to the extent that the exchange coupling magnetic fields of the two do not overlap,
Two kinds of antiferromagnetic layer materials having a small exchange coupling magnetic field dispersion are required. Further, in addition to these conditions, a material having characteristics of a high exchange coupling magnetic field and a high blocking temperature, which are essentially important when used in a spin valve element, cannot be easily found.

On the other hand, CoFe / Mn /
In a three-layer structure such as CoFe, magnetic orthogonal coupling between two ferromagnetic layers CoFe has been observed (J. Appl. Phys. 79 (8),
15 April 1996, etc.).

[0018]

SUMMARY OF THE INVENTION The present invention provides a novel magnetoresistive element devised under such circumstances, and in particular, a magnetoresistive element, a magnetoresistive head, and a magnetic head having a low manufacturing cost. It is an object to provide a reproducing device and a magnetic laminate.

[0019]

According to the present invention, there is provided a first ferromagnetic layer having a magnetization in a first direction,
A magnetic coupling layer formed by lamination with the first ferromagnetic layer; and a first ferromagnetic layer formed by lamination via the magnetic coupling layer. The first magnetic layer is magnetically coupled to the first ferromagnetic layer by the magnetic coupling layer. A second ferromagnetic layer having a magnetization in a direction substantially orthogonal to the direction, an intermediate nonmagnetic layer, and a second ferromagnetic layer laminated via the intermediate nonmagnetic layer. And a third ferromagnetic layer having a magnetization substantially in the same direction as the first ferromagnetic layer.

A second aspect of the present invention is a first ferromagnetic layer having a magnetization in a first direction, a mixed phase film containing two or more oxides of the same metal having different valences, or a valence of the same metal. A stacked film in which two or more oxide layers having different numbers are stacked,
An insertion layer laminated with the first ferromagnetic layer, a second ferromagnetic layer laminated with the first ferromagnetic layer via the insertion layer, and provided with magnetization in a direction substantially orthogonal to the first direction; An intermediate non-magnetic layer, and a third ferromagnetic layer laminated and formed with the second ferromagnetic layer via the intermediate non-magnetic layer and having a magnetization substantially in the same direction as the first direction in a state where the external magnetic field is zero. A magnetoresistive element is provided.

These magnetoresistive elements have a third ferromagnetic layer and a third ferromagnetic layer sandwiching the intermediate nonmagnetic layer in a state where the external magnetic field is zero.
The ferromagnetic layers have magnetizations that are substantially orthogonal to each other when the external magnetic field is zero. Then, the magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer are substantially orthogonal to each other by the magnetic coupling layer or the insertion layer. Therefore, the magnetization directions of the first and third ferromagnetic layers can be made substantially the same direction, so that the number of heat treatment steps for applying a magnetic bias can be reduced, and the manufacturing process can be simplified. Become.

The simplification of the process greatly contributes to the improvement of the productivity of the magnetic head, and it is possible to provide a magnetoresistive head with a low unit price and a magnetic reproducing apparatus.

The magnetic bias applied to the first and third ferromagnetic layers includes an exchange coupling bias using the first and second antiferromagnetic layers, respectively, and a hard magnetic layer instead of the antiferromagnetic layer. Or a stacked film of a plurality of ferromagnetic layers, a stacked film of a ferromagnetic layer and a non-magnetic phase, a stacked film of an antiferromagnetic layer and a ferromagnetic layer, and a stacked film of a hard magnetic layer and a ferromagnetic layer It is also possible.

In applying the magnetic bias,
The flexibility in selecting these homogeneous materials is obtained. For example,
When the antiferromagnetic layer is used for applying a magnetic bias, it is not necessary to provide a difference between the blocking temperatures of the two antiferromagnetic layers, and known materials such as IrMn, PtMn, and Fe
It can be appropriately selected from Mn, NiMn, NiO, α-Fe ₂ O _{3 and the} like.

It is preferable that the magnetoresistive element, the magnetoresistive head, and the magnetic reproducing apparatus of the present invention have the following configuration.

1) The second ferromagnetic layer is a magnetization free layer whose magnetization direction changes according to a change in an external magnetic field.
Is a magnetization pinned layer whose magnetization direction does not substantially change in an external magnetic field where the magnetization of the magnetization free layer changes. At this time, the magnetization of the first ferromagnetic layer may be configured to rotate according to the change in the magnetization direction of the second ferromagnetic layer or may be configured not to rotate. The second and third ferromagnetic layers can be magnetically decoupled from each other.

2) The third ferromagnetic layer is a magnetization free layer whose magnetization direction changes in accordance with the change of the external magnetic field, and the second ferromagnetic layer is a magnetization direction in an external magnetic field where the magnetization of the magnetization free layer changes. Is a magnetization pinned layer that does not substantially change.
At this time, it is preferable that the magnetization of the first ferromagnetic layer does not substantially change in an external magnetic field where the magnetization of the magnetization free layer changes. Note that the second and third ferromagnetic layers can be magnetically decoupled from each other.

3) The first antiferromagnetic layer is formed only on both ends in the longitudinal direction of the first ferromagnetic layer. And / or the second antiferromagnetic layer is formed only at both ends in the longitudinal direction of the third ferromagnetic layer.

4) The first antiferromagnetic layer is formed so as to cover one entire surface of the first ferromagnetic layer.

5) A nonmagnetic layer is further provided between the first antiferromagnetic layer and the first ferromagnetic layer or between the second antiferromagnetic layer and the third ferromagnetic layer.

6) The first, second, and third ferromagnetic layers are:
It has two ferromagnetic layers and an intermediate layer for antiferromagnetic coupling for magnetically coupling the two ferromagnetic layers. The two antiferromagnetically coupled ferromagnetic layers and the intermediate layer constitute a unit called a so-called synthetic antiferromagnetic film. Since the two ferromagnetic layers are antiparallel to each other, the magnetic field closes inside the unit and the external And the bias point can be suitably controlled.

7) The magnetic coupling layer or the insertion layer is a multiphase film containing two or more kinds of oxides of the same metal having different valences, or two or more oxide layers of the same metal having different valences are laminated. It has a laminated film. Here, oxides of the same metal having different valences are as follows: 7-1) FeO, Fe ₃ O ₄ , α-Fe ₂ O ₃ , γ-Fe ₂
O ₃ 7-2 selected _{from) CrO, Cr 2 O 3,} CrO 2, Cr 2 O 5, Cr
It is selected from O ₃ and CrO ₅ .

7-3) MnO or MnO _{2 is} selected.

8) The magnetic coupling layer or the insertion layer is an insulating layer such as an oxide, and further includes a new insulating layer sandwiching the intermediate non-magnetic layer together with the magnetic coupling layer, so that electrons can be generated at the interface between the insulating layers. Specular reflection is induced, and the reflected electrons come back to the interface with the intermediate nonmagnetic layer. This electron reflection layer is known as the specular effect.

9) By the magnetic coupling layer or the insertion layer,
When an external magnetic field is applied, the first and second ferromagnetic layers orthogonally coupled to each other cause the following two types of magnetization rotation depending on the selection of a material or the like.

9-1) The orthogonal coupling is broken, the exchange coupling between the first ferromagnetic layer and the first antiferromagnetic layer is maintained, and only the second ferromagnetic layer rotates.

9-2) The orthogonal coupling is maintained and the coupling between the first ferromagnetic layer and the first antiferromagnetic layer is broken, so that the first and second ferromagnetic layers are not affected by an external magnetic field. The magnetization rotates.

The magneto-resistance effect head of the present invention is a so-called shield type head in which the magneto-resistance effect element is arranged in a magnetic gap near the medium facing surface of the magnetic head. The dispersion of the exchange coupling magnetic field of the exchange coupling film is increased by reducing the thickness of the antiferromagnetic layer. However, according to the present invention, it is not necessary to avoid the overlapping of the dispersion, so that the thinning of the antiferromagnetic layer can be easily realized. it can. Such thinning of the antiferromagnetic layer is suitable for narrowing the gap of the shield type magnetoresistive head, and has the effect of contributing to higher density.

11) A yoke type in which a magnetoresistive element is disposed apart from the medium facing surface, and has a magnetic yoke extending from the medium facing surface to the magnetoresistive element and transmitting a signal magnetic field from the medium to the magnetoresistive element. This is a magnetoresistive head. Since the number of heat treatments for applying a bias can be reduced in the magnetoresistive effect element of the present invention, it is difficult for the yoke portion to have uniform magnetic anisotropy, and an efficient transfer from the medium facing surface to the magnetoresistive effect element is achieved. The introduction of magnetic flux can be expected.

A third aspect of the present invention is a first ferromagnetic layer having a magnetization in a first direction, and a second ferromagnetic layer having a second magnetization substantially perpendicular to the first direction. , First and second
A multi-phase film containing two or more oxides of the same metal with different valences, or a laminate containing two or more oxide layers of the same metal with different valences A magnetic laminate comprising: an interlayer film comprising a film;

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the magnetoresistive element according to the present invention will be described with reference to FIG.

FIG. 1 is a perspective view showing a magnetoresistive element. The front surface in FIG. 1 corresponds to the entrance surface of the external magnetic field detected by the magnetoresistive element. Therefore, for example, when this magnetoresistive element is mounted on a shielded magnetic head that reads out magnetically recorded information on the surface of a magnetic recording medium, an external magnetic field entry surface is arranged to face the surface of the magnetic recording medium.

The magnetoresistive element according to the first embodiment includes a first antiferromagnetic layer 31 and a first antiferromagnetic layer 31.
A first ferromagnetic layer 33 exchange-coupled with the first antiferromagnetic layer 31, a magnetization coupling layer (insertion layer) 35 for coupling the magnetizations of two adjacent ferromagnetic layers in a substantially orthogonal direction,
The coupling layer 35 causes the second ferromagnetic layer 37 and the intermediate non-magnetic layer 3 having magnetization perpendicular to the first ferromagnetic layer 33.
9, and a pair of second antiferromagnetic layers 43 formed on both ends of the third ferromagnetic layer 41 in the longitudinal direction, and a pair of leads. An electrode 45 is provided. The magnetoresistive element is formed on a ceramic substrate or the like (not shown) via a magnetic gap or a magnetic shield (not shown).

The first ferromagnetic layer 33 has a magnetization substantially fixed in the direction of the arrow in FIG. 1 (rightward in the drawing) by exchange coupling with the first antiferromagnetic layer 31. The magnetization of the first and second ferromagnetic layers 33 and 37 is the same as the coupling layer 3 for orthogonal magnetization.
5, the magnetization of the second ferromagnetic layer 37 is fixed substantially in the direction from the front to the back of the paper. The second ferromagnetic layer 37 having the magnetization fixed as described above corresponds to a so-called ferromagnetic pin layer whose magnetization does not substantially move even in an external magnetic field such as a signal magnetic field.

The ferromagnetic pinned layer 37 and the intermediate nonmagnetic layer 39
The third ferromagnetic layer 41 adjacent to the third ferromagnetic layer corresponds to a ferromagnetic free layer, and the direction of magnetization of the central magnetic field response portion is free enough to rotate by receiving an external magnetic field. In order to apply a magnetic bias to the ferromagnetic free layer 41,
The second antiferromagnetic layer 43 is disposed on both ends (hatched portions) in the track width direction of the ferromagnetic free layer 41, and both ends of the ferromagnetic free layer 41 are exchanged with the second antiferromagnetic layer 43. As a result, the magnetization is fixed in the direction of the arrow in the figure (rightward on the paper). Therefore, the central portion of the ferromagnetic free layer 41 receives a rightward bias magnetization in the plane of the paper, and has a magnetization in a direction indicated by an arrow in FIG. 1 at zero magnetic field. Thus, the ferromagnetic pinned layer 37 and the ferromagnetic free layer 41 via the intermediate nonmagnetic layer 39 can realize a so-called spin valve element in which the magnetizations are orthogonal.

In the configuration shown in FIG. 1, the horizontal direction of the drawing corresponds to the track width direction of the magnetoresistive element, and the reproduction track width substantially matches the width of the central magnetic field response portion of the ferromagnetic free layer.

In this spin valve element, the exchange coupling between the first ferromagnetic layer 33 and the ferromagnetic free layer 41 can be performed in the same direction. This can be achieved by adding a coupling layer 35 for orthogonal coupling and a first ferromagnetic layer 33, which are not included in the conventional spin valve element.

In the heat treatment step in a magnetic field in the manufacturing process of the spin valve element, the blocking temperature (for example, T _B1 ,
T _B2 ) can be carried out by processing in a magnetic field in one direction (rightward direction in the drawing of FIG. 2) at a temperature higher than T _B2 ). This is simpler than the conventional two-step magnetic field heat treatment,
As a result, it contributes to the improvement of the productivity of the spin valve element. In FIG. 2, AF indicates an antiferromagnetic layer, and since the antiferromagnetic layer has uniaxial anisotropy, the bidirectional arrow indicates the uniaxial anisotropy. In addition, the heat treatment step described above
This is performed after forming each layer by a sputtering method or the like.

The first embodiment described above is a bottom type spin valve element in which the ferromagnetic pinned layer 37 is formed closer to the substrate than the ferromagnetic free layer 41, and the coupling layer 35 is formed of a ferromagnetic pinned layer. It relates to the element structure on the layer 37 side.

Next, a first modification of the first embodiment will be described.
-1 to 1-4 will be sequentially described. Note that in Modifications 1-1 to 1-4, the same components as those in the first embodiment will be denoted by the same reference numerals as those in the first embodiment, and detailed description thereof will be omitted.

(Modification 1-1) FIG. 3 is a diagram in which a cross section of the spin valve element according to Modification 1-1 is observed from the medium facing surface.

This modified example 1-1 is different from the first embodiment in that the inner ends of the lead electrodes 45 are arranged inside the side surfaces of the second antiferromagnetic layer 43 facing each other, and are strong. This is in that a part of the magnetic free layer 41 is covered. FIG.
The hatched portion of the middle and ferromagnetic free layer 41 is the second
Since the magnetization is fixed by exchange coupling with the antiferromagnetic layer 43, a dead zone which does not react to the signal magnetic field is provided, and a central region sandwiched between the dead zones is a central magnetic field response section. Therefore, since the lead electrode is in contact with the central response portion, a dead zone that does not contribute to the magnetoresistance effect can be electrically bypassed, and the sensitivity can be improved.

Reference numeral 47 in FIG. 3 and subsequent figures denotes a magnetic gap or an underlayer formed on the surface of the magnetic gap. The material, crystallinity, and the like of the underlayer 47 can be appropriately selected so as to make the type of crystal, the crystal orientation, and the like in each layer formed thereon suitable.

(Modification 1-2) Next, FIG.
2 is a diagram showing a cross section of the spin valve element of No.-2 observed from the medium facing surface.

The modification 1-2 is different from the first embodiment in that the antiferromagnetic layer 43 'is laminated on the entire upper surface of the ferromagnetic free layer 41.

When the antiferromagnetic layer 43 ′ and the ferromagnetic free layer 41 are entirely stacked as described above, the exchange coupling force becomes
When the external magnetic field is zero, the magnetization of the ferromagnetic free layer 41 is in the rightward direction in the drawing of FIG. 4 and can rotate freely in response to the external magnetic field when applied. There is a need.

However, in the exchange coupling by lamination on the entire surface, the coupling is apt to be strong, and the magnetic permeability of the ferromagnetic free layer 41 may be reduced to lower the sensitivity.

(Modification 1-3) In order to prevent this decrease in sensitivity, in modification 1-3, as shown in the cross-sectional view of FIG. 5 (view from the medium facing surface side), the second antiferromagnetic By inserting the non-magnetic layer 49 between the layer 43 'and the ferromagnetic free layer 41, the exchange coupling force can be adjusted to a desired value.

The modifications 1-2 and 1-3 can be similarly applied to the second to fourth embodiments described later.

Further, the nonmagnetic layer 49 for adjusting the magnetic coupling of the modified example 1-3 is the same as the modified example 1-2, except that the antiferromagnetic layer 43 ′ is adjacent to the nonmagnetic layer 49 via the nonmagnetic layer 49. Not only the structure covering the entire upper surface of the ferromagnetic layer but also the case where the antiferromagnetic layer is formed on the partial region of the ferromagnetic layer in the first embodiment or the second to fourth embodiments described later. It can be inserted and used like this.

(Modification 1-4) FIG. 6A shows a modification 1
FIG. 4 is a diagram in which a cross section of the spin valve element relating to No. -4 is observed from the medium facing surface side.

In the spin valve element according to the first embodiment,
When the exchange coupling energy for fixing the magnetization of the ferromagnetic pinned layer 37 is fixed, the magnetization reversal becomes more difficult as the magnetization of the ferromagnetic pinned layer 37 decreases. Therefore, the ferromagnetic pinned layer is formed into a laminated ferrimagnetic structure, specifically, as shown in FIG. 6A, the first ferromagnetic pinned layer 55, the second ferromagnetic pinned layer 51, and With the laminated structure including the intermediate layer 53 that is magnetically coupled, the magnetization reversal of the ferromagnetic pinned layer 37 can be suppressed. In the structure shown in FIG. 6A, the magnetic field for maintaining the orthogonal coupling can be increased by introducing the laminated ferrimagnetic structure. Therefore, the magnetic field at which the magnetization reversal of the magnetic layers 33, 51, 55 occurs can be extremely high.

As another example in which a laminated ferrimagnetic structure is introduced, as shown in FIG. 6B, a first antiferromagnetic layer 31 is formed.
The ferromagnetic layers 57 and 33 having a laminated ferri structure and the intermediate layer 53 for magnetically coupling these ferromagnetic layers antiferromagnetically are introduced between the ferromagnetic layers 57 and 33 and the magnetic coupling layer (insertion layer) 35 for orthogonal coupling. be able to. In this case, the first antiferromagnetic layer 31
And the exchange coupling magnetic field of the laminated ferri structure can be increased. The intermediate layer 53 in the laminated ferrimagnetic structure has Ru,
Cu and the like are preferred.

(Second Embodiment) Next, a second embodiment of the magnetoresistive element of the present invention will be described with reference to FIG.

FIG. 7 is a diagram showing a cross section of the spin valve element according to the second embodiment, which is observed from the entrance surface of the external magnetic field.

As shown in FIG. 7, the second spin valve element comprises a first antiferromagnetic layer 61, a ferromagnetic pinned layer 63, an intermediate nonmagnetic layer 65, and a ferromagnetic free layer formed on the surface of an underlayer 47. 6
7, a magnetic coupling layer 69 for orthogonal coupling, and a ferromagnetic layer 71 are stacked in this order, a second antiferromagnetic layer 73 is formed on both ends of the upper surface of the ferromagnetic layer 71, and a lead electrode 75 is provided. They are electrically connected to these films.

This spin valve element has a ferromagnetic pin layer 6
Reference numeral 3 denotes a bottom type formed on the base layer side with respect to the ferromagnetic layer 67, and a magnetic coupling layer (insertion layer) 69 for orthogonal coupling is provided on the ferromagnetic free layer 67 side. The lead electrodes 75 are the same as those described in the first embodiment.

The hatched portions at both ends of the ferromagnetic layer 71 are regions fixed by magnetization in the direction from the front to the back of FIG. 7 by exchange coupling with the second antiferromagnetic layer 73, and are located in the central active region. This is to apply a magnetic bias in the magnetization direction. As a result, the magnetization of the central region of the ferromagnetic layer 71 is set in a direction from the front to the back of FIG. 7 when the external magnetic field is zero.

Then, as shown in FIG. 7, the ferromagnetic free layer 67 provided with the magnetic coupling in the orthogonal direction to the ferromagnetic layer 71 by the intermediate layer for orthogonal coupling has the magnetization in the right direction on the paper, as shown in FIG. When the magnetic field is zero, orthogonal magnetization of the ferromagnetic pinned layer 63 and the ferromagnetic free layer 67 can be realized.

(Modification 2-1) As described above, the magnetizations of the ferromagnetic pinned layer 63 and the ferromagnetic free layer 67 are crossed substantially orthogonally using the two antiferromagnetic layers 61 and 73 having the same axis of magnetization. Can be done.

FIG. 8 shows a modification of the second embodiment, in which a ferromagnetic layer 71 'in contact with a second antiferromagnetic layer 73' and an intermediate layer 69 'for orthogonal coupling have two FIG. 13 is a view of a cross-sectional structure patterned so as to be aligned with each of the antiferromagnetic layers 73 ′ of FIG. By doing so, the shunt effect of the current can be reduced, and the contribution of the magnetoresistance change rate due to the magnetization reversal can be substantially increased.

(Third Embodiment) Next, a third embodiment according to the magnetoresistance effect element of the present invention will be described with reference to FIG.

FIG. 9A is a view of a cross section of the spin valve element according to the third embodiment, as viewed from a plane into which an external magnetic field enters.

As shown in FIG. 9A, the spin valve element according to the third embodiment includes a first antiferromagnetic layer 81, a ferromagnetic free layer 83, an intermediate nonmagnetic layer on an underlayer 47. Layer 8
5, a ferromagnetic pinned layer 87, a magnetic coupling layer 89 for orthogonal coupling,
The coupling layer 89 has a structure in which a ferromagnetic layer 91 magnetically coupled substantially orthogonally to the ferromagnetic pinned layer 87, a second antiferromagnetic layer 93 exchange-coupled to the ferromagnetic layer 91, and a lead electrode 95 are sequentially stacked. Prepare.

The first antiferromagnetic layer 81 is exchange-coupled with both ends of the ferromagnetic free layer 83 (hatched portions in FIG. 9A). 9 applies a bias magnetic field to the central magnetosensitive region of the ferromagnetic free layer 83, and when the signal magnetic field is zero, the magnetosensitive region is in FIG.
It has the magnetization indicated by the arrow in FIG.

In this device, two antiferromagnetic layers 81 used to fix the magnetization of the ferromagnetic pinned layer 87 and to apply a bias to the ferromagnetic free layer 83, as described in the first embodiment. , 93 can be reduced as compared with the prior art.

In the third embodiment, there is no need for the ferromagnetic free layer 83 between the two first antiferromagnetic layers 81 that are spaced apart from each other, and the medium facing surface shown in FIG. As shown in a sectional view observed from the side, a spacing layer 97 may be used. This spacing layer 97 is made of Al used for a magnetic device such as a magnetic head in order to reduce the shunt effect.
Insulating materials such as O _x and SiO _x are preferred. Further, in order to enhance the crystal orientation of the ferromagnetic free layer 83, Cu, Ru,
NiFe, NiFeCr, or the like can be used. Furthermore, different material layers may be laminated or a mixed layer may be used.

(Fourth Embodiment) FIG. 10 is a diagram in which a cross section of a spin valve element according to a fourth embodiment of the present invention is observed from a signal inflow surface.

As shown in FIG. 10, the spin valve element according to the fourth embodiment has two first antiferromagnetic layers 101 and two first antiferromagnetic layers 101 formed separately from each other on an underlayer 47.
Layer 10 extending between and above the antiferromagnetic layers 101
3. The magnetic coupling layer 105 for magnetically coupling the ferromagnetic layer 103 and the ferromagnetic free layer 107 so that the magnetizations thereof are substantially orthogonal to each other, the ferromagnetic free layer 107, the intermediate nonmagnetic layer 109,
A ferromagnetic pin layer 111, a second antiferromagnetic layer 113, and a lead electrode 115 are provided.

FIG. 11 shows that the third antiferromagnetic layer 101 is separated from the third antiferromagnetic layer 101 in the fourth embodiment.
As described in the embodiment, the spacing layer 117
FIG. 5 is a diagram of a cross section of the spin valve element in which is disposed, observed from the inflow surface side of the external magnetic field. The material described in the third embodiment can be used for the spacing layer 117.

In FIGS. 10 and 11, of the ferromagnetic layer 103, both end portions (hatched portions in FIGS. 10 and 11) laminated on the first antiferromagnetic layer 101 are the first antiferromagnetic layer. The magnetization is fixed by exchange coupling with the ferromagnetic layer 101,
The central magnetically sensitive region sandwiched between the two ends has magnetization from the front to the back of the page due to the magnetic bias from the two ends.

The ferromagnetic pin layer 111 is the antiferromagnetic layer 1
13, the magnetization of the ferromagnetic pinned layer 1 is also turned down from the front of the paper.
11 and the number of heat treatment steps required for applying a magnetic bias to the ferromagnetic layer 103 can be reduced, and the same effects as described in the other embodiments can be obtained.

The magnetoresistive elements according to the first to fourth embodiments and their modifications have been described with reference to the drawings.

Next, the material used for the magnetic coupling layer (intermediate layer) for orthogonal coupling and the orthogonal coupling in the present invention will be described.

As the magnetic coupling layer (intermediate layer), a multi-phase film containing two or more kinds of oxides of the same metal having different valences, or a laminate in which two or more oxide layers of the same metal having different valences are stacked. A membrane can be used. Here, oxides having different valences include: 1) an oxide of Fe, FeO, Fe ₃ O ₄ , α-F
e ₂ O ₃ or γ-Fe ₂ O ₃ . 2) an oxide of _{Cr, CrO, Cr 2 O 3} , CrO
_{2, Cr 2 O 5, CrO} 3, selected from CrO _5. 3) The oxide having a different valence is composed of an oxide of Mn.
It is selected from nO and MnO ₂ .

Further, Au, Al, A
g, any of Cu, Cr, Mn, etc., a mixed layer thereof,
Alternatively, it can be realized by a laminated film of a single element layer and a mixed layer.

The two unit ferromagnetic layers of the ferromagnetic layer / intermediate layer for orthogonal coupling / ferromagnetic layer in which two ferromagnetic layers are stacked via the intermediate layer for orthogonal coupling have a unit vector of magnetization M ₁ , M ₂ , the binding energy Ec between the ferromagnetic layers
Is It is represented by Here, A ₁₂ is a normal bilinear exchange coupling constant, and B ₁₂ is a biquadratic exchange coupling constant. Substantially 90 degree (orthogonal) coupling occurs when | A ₁₂ | <| B ₁₂ | and B ₁₂ <0.

B ₁₂ is induced when the antiferromagnetic coupling state where A ₁₂ <0 and the ferromagnetic coupling state where A ₁₂ > 0 coexist. On the other hand, since A ₁₂ vibrates as the thickness of the intermediate layer increases, the film thickness distribution occurs when the actual sample has irregularities, and as a result, A ₁₂ <0 and A
_A mixture of ₁₂ > 0 results in approximately 90 ° coupling. When surface irregularities of one atom are present in the intermediate layer at a period of 2L, and the difference in bilinear binding energy due to the irregularities is 2ΔJ, the biquadratic coupling constant B ₁₂ is represented by B ₁₂ = − [2 (ΔJ) ² L / (Aπ ³ )] Σm ₌ 1∞ [coth [π (2m−1) (D ₁ / L)] / (2m−1) ³ + coth [π (2m−1) (D ₂ / L)] / (2m-1) ³ ] (2) (Phys. Rev. B 67, 3172 (1991)).

Here, D ₁ and D ₂ represent the thicknesses of the two ferromagnetic layers, respectively, and A is the exchange stiffness constant inherent to the ferromagnetic material. As can be seen, B ₁₂ depends largely on the smoothness and thickness of the film. Therefore variations in B ₁₂ by setting the conditions of sample preparation are expected to appear. By epitaxial growth, to create a three-layer film made of different ferromagnetic layer / orthogonal coupling intermediate layer / ferromagnetic layer, the B ₁₂ obtained and their orientation plane, are shown in Table 1.

[0090]

[Table 1]

In Table 1, ML is a unit of an atomic layer, and 1 ML represents one atomic layer.

The thickness of the intermediate layer for orthogonal coupling is desirably about 0.2 nm to 2 nm, which is a range in which 90 ° coupling can be realized.

Further, as the intermediate layer for orthogonal coupling of the present invention,
In addition to the materials mentioned above, metal oxides, metal nitrides and metal fluorides are conceivable. Among these, if the material contains a metal whose magnetism varies depending on the valence, a mixed phase state of ferromagnetic, antiferromagnetic, and ferrimagnetic phases is realized by controlling the progress of oxidation, nitridation, and fluorination. can do.

For example, Fe oxides (FeO, Fe ₃ O ₄ ,
α-Fe ₂ O ₃ , γ-Fe ₂ O ₃ ), a mixed phase film thereof, or a laminated film. The thickness of these orthogonal coupling intermediate layers is about 0.2 nm to about 10 nm, preferably about 0.5 nm to about 3 nm. Example 1 Regarding Spin Valve Film Using Fe Oxide for Intermediate Layer for Orthogonal Coupling
4 to 4, it was confirmed that the Fe oxide couples the magnetization of the adjacent ferromagnetic layer, and the binding energy was measured as follows.

In Examples 1 to 4, films were sequentially formed on thermally oxidized Si using a DC magnetron sputtering method. Then, while applying a magnetic field of 7 kOe in a vacuum, the thermal oxidation S
i was heated to 270 ° C. and heat-treated for 1 hour. Thus, the exchange coupling energy Jua = Hua · Ms · t ≒ 0.14 erg / at the IrMn / CoFe interface in each example.
The magnetization of CoFe is fixed by cm ² . Where Hu
a is the exchange coupling magnetic field (here, 500 Oe), Ms is the saturation magnetization of the pinned layer (1.8 T), and t is the thickness of the pinned layer (2 nm).
It is. Table 2 shows the layer configuration of each example. Each example is
In the order from the left of Table 2, they were formed on a thermally oxidized Si substrate by the above-described method.

[0096]

[Table 2]

Here, langmuire is a unit relating to the oxidation strength, and indicates the amount of oxide formed when exposed to an atmosphere having an oxygen partial pressure of 1 × 10 ⁻⁶ Torr for 1 second.

FIG. 12A shows the magnetization curve and the MR curve of Example 1 in which Fe oxide was used for the intermediate layer for orthogonal coupling.
(C) and FIGS. 12 (b) and 12 (d). The magnetization curve and MR when an external magnetic field (Hex) is introduced in parallel to the exchange bias magnetic field direction (Hua) from the IrMn antiferromagnetic layer.
The curves are FIGS. 12 (a) and 12 (c), and the magnetization curves and MR curves when introduced perpendicularly are FIGS. 12 (b) and 12 (d).
When Hua and Hex are parallel, the MR change rate is less than 8%,
Hua and Hex exhibited an MR change rate of slightly more than 10% when perpendicular. Considering that the MR shows the maximum value when the magnetization of the CoFe ferromagnetic free layer and the CoFe ferromagnetic pinned layer sandwiching the Cu intermediate nonmagnetic layer is completely antiparallel, it is considered that the parallel Sometimes, it can be seen that the magnetizations of the free layer and the pinned layer are not completely anti-parallel, and anti-parallelism is realized during vertical insertion. That is, Co whose magnetization is fixed by the exchange bias magnetic field from IrMn is
It can be said that the magnetization of the Fe ferromagnetic layer and the magnetization of the CoFe ferromagnetic pinned layer that exists with the orthogonal coupling intermediate layer formed of the ferromagnetic layer and the Fe oxide are substantially orthogonal.

In the first embodiment, when an external magnetic field was applied, the magnetic field at which the magnetization of the CoFe ferromagnetic pinned layer and the CoFe free layer became antiparallel was about 380 Oe. This means that the magnetic coupling energy of the Fe oxide is 0.11 erg / cm ² or more.

In Example 2, the oxidation strength in the natural oxidation of the intermediate layer for orthogonal coupling was changed.

FIG. 13 shows the oxidative strength dependence of the magnetic field H ₉₀ ° at which the antiparallel state is broken and the rate of change in electric resistance when the magnetic field is vertically inserted. In 600 Langmuiers, the Fe oxide necessary for bonding at 90 degrees is not formed, and 1200
Above Langmuiers, 90 degree coupling is realized.

When the orthogonal coupling intermediate layer is made of an insulating material, an effect of increasing MR by electron reflection can be obtained. It is considered that Cu and Ta form a Cu-Ta oxide by self-oxidation, and this Cu-Ta oxide and CoF
e Since specular reflection of conduction electrons occurs at the interface between the ferromagnetic free layer and the interface between the Fe oxide and the ferromagnetic pinned layer, about 10% of the MR in the spin valve without the Fe oxide is MR. In contrast to the maximum value, an MR of 13% was obtained for the 1200 Langmuiers of Example 2 using Fe oxide.
was gotten. However, if the oxidation is made stronger than 1200 Langmuiers, the MR gradually decreases because the film surface becomes rough.

Therefore, in order to achieve both stable magnetic coupling and high MR, 1000 Langmuiers to 8000 La
An oxidation strength of about ngmuiers is appropriate.

Next, in Example 3, the thickness of the IrMn antiferromagnetic layer and the intermediate layer for orthogonal coupling of the Fe oxide was examined. Table 3 shows the results.

[0105]

[Table 3]

Thus, in order to achieve good magnetic coupling, the thickness of the CoFe ferromagnetic layer sandwiched between the IrMn antiferromagnetic layer and the Fe oxide intermediate layer should be at least 1 nm or more, preferably 2 nm or more. It can be seen that it is. However, if the thickness is too large, the magnetization (Ms · t product) increases and Hua decreases, so the thickness should be 2 nm or more and 3 nm or less.

In Example 4, the thickness of Fe before oxidation of the intermediate layer for orthogonal coupling was changed. Here, the oxidation strength is
When the Fe content is 2 nm or less, it is 3000 Langmuirs, and when it is 2 nm or more, it is 12000 Langmuirs. The reason why the oxidation strength was changed in accordance with the thickness of Fe was to take into account that even if the Fe was thick, it was oxidized to a deep layer, but as described above,
In the region where the oxidation was strong, the film surface was rough and the MR was lowered. FIG.
FIG. 4 shows the relationship between the Fe film thickness, the orthogonal coupling magnetic field H ₉₀ °, and the rate of change in electric resistance. From these results, it can be said that the thickness of Fe is preferably 1 nm to 3 nm. In particular, 1.5 nm to 2 nm
Is more desirable.

In Example 5, the MR curve of a spin valve obtained by naturally oxidizing Cr to form an orthogonal coupling intermediate layer is shown in FIG.
Shown in Although the 90 degree coupling magnetic field is smaller than that of Fe, it is about 50 Oe (in this case, 0.014 erg / c
m ² ).

Here, by introducing oxygen into the film forming chamber, Fe,
Examples 1-5 in which Cr was naturally oxidized were described.
In addition to Cr, Mn can be used. Other examples of the oxidation method include (1) oxidation by oxygen radical generated by plasma, and (2) oxygen radical generated by irradiating ultraviolet rays from an excimer lamp. Oxidation,
(3) Reactive sputtering of Fe, Cr, and Mn in an atmosphere containing oxygen can be considered. (1) is suitable for forming a dense and thin oxide film, and makes it easy to control the valences of Fe, Cr and Mn. In (2), in addition to (1), damage due to oxygen ions is small, and a smooth interface can be formed. This enhances the effect of electron specular reflection,
Output can be improved. In (3), a chemically stable oxide film is obtained, and stable operation as an element can be continued. Further, in (1) to (3), the substrate is kept at 40 ° C. to 1
When the oxidation proceeds while heating to 00 ° C., the oxide can be obtained in a smooth and chemically stable state. In (1) and (2), when the substrate is cooled to 77 K to 295 K and oxidized, the dissociation of oxygen molecules and spontaneous oxidation can be suppressed, so that the contribution of oxygen radical increases,
A dense and thin oxide film can be formed.

Although the thermally oxidized Si is used here as the substrate, a sapphire substrate,
It is also possible to use an MgO substrate, a GaAs substrate, or a Si substrate. Further, as a measure for reducing the noise of the element, the soft magnetic characteristic base of the free layer is made of a metal having an fcc structure instead of NiFe, for example, Ru, Cu, Au, NiFeC.
Alternatively, a single-layer film, a laminated film thereof, or a mixed-phase film may be used.

By the way, in order to insert an intermediate layer for orthogonal coupling between the ferromagnetic free layer and the antiferromagnetic layer, a device for improving the sensitivity as a spin valve is required.
When the two ferromagnetic layers sandwiching the orthogonal coupling intermediate layer have the same magnetization (Ms · t product), the magnetization of the entire ferromagnetic free layer is oriented at 45 degrees with respect to the ferromagnetic pinned layer. Therefore, even when an external magnetic field is applied from the recording medium, the magnetization may be difficult to rotate.

To prevent this, the two
The difference is to provide a difference in the Ms · t product so that the added magnetization of the ferromagnetic layers of the layers is substantially orthogonal to the magnetization of the pinned layer.
If the ratio of the Ms · t product of the ferromagnetic free layer and the ferromagnetic layer in contact with the antiferromagnetic layer is about 1: 5, the magnetization of the ferromagnetic pinned layer and the magnetization through the orthogonal coupling intermediate layer are The angle formed by the ferromagnetic magnetization is about 80 deg., And the sensitivity degradation can be suppressed.

Further, there is a method of weakening orthogonal coupling. While the magnetization of the ferromagnetic layer in contact with the antiferromagnetic layer remains fixed, only the magnetization of the ferromagnetic free layer rotates. In this case, as the sensitivity, the external magnetic field at which the magnetization of the ferromagnetic free layer starts to rotate is preferably 5 Oe or less. For example, when the magnetization of the ferromagnetic free layer is 3.6 nmT, the orthogonal coupling energy is 1.4 × 10 ^{−. It} needs to be ³ erg / cm ² or less.

The above-described magnetoresistive element using the magnetic coupling layer (insertion layer) that couples substantially orthogonally can be used as a reproducing head of a magnetic reproducing device such as a magnetic disk device.

Among the magnetic read heads, the shield type magnetic head used so far has the above-described magnetoresistive element near the medium facing surface of the head.

In addition to the shield type magnetic head, FIG.
6 can also be applied to a yoke type magnetic head shown in a schematic perspective view. As shown in FIG. 16, this yoke type magnetic head has:
A pair of yokes 1204 are provided on the medium facing surface 1200 to spread a signal magnetic field from a recording track 1202 on the recording medium and guide the signal magnetic field to a magnetoresistive element disposed inside the head. In practice, the recording medium rotates in the plane, and the magnetic heads move relative to each other on the surface via air or in contact with each other.

In FIG. 16, arrows attached to the pair of yokes indicate the direction in which the signal magnetic field enters. This signal magnetic field is applied to the yoke 1
One of the yoke 1204 leads to the magnetoresistive element 1210 of the present invention disposed behind the medium facing surface 1200 and returns to the medium by the other of the yokes 1204, thereby forming one magnetic circuit. The magnetoresistive element 1210 includes a magnetoresistive film 1206 and a pair of lead electrodes 1208 connected to both ends of the magnetoresistive film 1206. Dotted arrows on the magnetoresistive film 1206 and the lead electrodes indicate the direction of the sense current.

When such a yoke 1204 is used, it is desirable that the yoke 1204 has a high magnetic permeability in order to efficiently guide the magnetic flux to the magnetoresistive film 1206. It is desirable not to have.
However, the heat treatment for the spin valve is not performed on the yoke 1204.
The yoke may have a uniform magnetic anisotropy due to the heat treatment of the spin valve. Therefore, it is a great advantage of the yoke type magnetic head that the heat treatment can be reduced as in the magnetoresistive element of the present invention. The advantage of such a yoke type magnetic head is not limited to the structure shown in FIG.
The same effect can be obtained if the magnetoresistive element is arranged at a position retreated from the medium facing surface and the medium facing surface and the magnetoresistive element are bridged by a magnetic yoke.

In the yoke type head, the design is such that the lead electrodes 1208 are arranged at positions facing each other in the x direction as shown in FIG. This is because the main surface 1206 of the magnetoresistive film is formed on the magnetic medium 120 as shown in FIG.
2 and a structure formed on the rear surface of the yoke 1204 and parallel to the magnetic medium 1202.

The flow of the magnetic flux in the magnetoresistive film is shown in FIG.
As shown by the arrow in the middle, it faces the x direction. That is, the sense current and the direction of the magnetic flux flowing into the ferromagnetic free layer 7 are parallel or anti-parallel. In such a situation, when a conventional spin valve that does not use substantially orthogonal is mounted, FIG.
(A) An antiferromagnetic layer 9 for applying a magnetic bias (magnetic domain control) to the ferromagnetic free layer 7 is arranged so as to face the middle z direction. That is, a shunt current flows in a magnetic field insensitive region where the magnetic domain control antiferromagnetic layer is in contact with the free layer, and the output is reduced.

On the other hand, if a spin valve element using a magnetic coupling layer (insertion layer) 12065 of substantially orthogonal coupling is mounted, as shown in FIG.
In the magnetic domain control of No. 4, the antiferromagnetic layers 12067 are arranged to face each other in the x direction via a magnetic bias to the ferromagnetic layer 12066, and the lead electrode 1208 is extended to a central active region that is more central than the antiferromagnetic layer 12067. Thus, the magnetic field insensitive region of the ferromagnetic free layer 12064 can be bypassed. From this, it can be said that the combination of the yoke type magnetic head and the spin valve element using the magnetic coupling layer (insertion layer) 12065 for substantially orthogonal coupling produces a great advantage from the viewpoint of improving the output.

Further, as shown in the perspective view schematically showing the yoke type magnetic head of FIG. 18, the main surface (the surface perpendicular to the film deposition direction) of the magnetoresistive film 1206 is set to the magnetic recording medium 12.
02, a pair of hard magnetic material layers or antiferromagnetic material layers 12067 are sandwiched between the magnetoresistive film 1206a and the track width forming portion above the track of the recording medium. , The magnetization of the yoke 1204 can be aligned in the y direction. By doing so, the magnetic permeability in the x direction of the yoke becomes uniform and small, and the signal magnetic flux from the recording medium 1202 efficiently flows into the free layer. At this time, the magnetization of the pinned layer of the magnetoresistive film 1206a needs to be fixed in a perpendicular relationship (x direction) with the magnetization of the yoke and the free layer. That is,
Heat treatment for fixing the magnetization of the pin layer and heat treatment for fixing the magnetization of the yoke 1204 are required. Here, by inserting the orthogonal coupling film into the pin layer or the free layer, the yoke 1204 and the pin layer can be simultaneously heat-treated by inserting the orthogonal coupling film into the pin layer or the free layer. Thus, the number of manufacturing steps can be reduced. Note that the magnetoresistive film described in each embodiment can be used for the magnetoresistive film 1206a in FIG. 18, and the detailed description is omitted here. Note that FIG.
In the yoke type head as shown in FIG. 1, a GMR of a current flowing perpendicularly to the main surface (CPP method) is used as a magnetoresistive element.
Elements are suitable. In this case, the pair of electrodes are arranged so as to sandwich the magnetoresistive film from above and below.

The above-described film structure using a substance which is bonded substantially orthogonally can be applied to not only a spin valve but also a so-called dual spin valve element having an artificial lattice film and a double spin valve structure. Further, a tunnel magnetoresistive film using a tunnel effect or a CPP (Curr) in which a sense current flows in a direction perpendicular to the film surface of the magnetoresistive film.
ent Perpendicular to Plan
e) It can be applied to a magnetoresistance effect element. FIG. 19 shows a cross section of an example.

This tunnel magnetoresistive element has a structure in which the first antiferromagnetic layer 12 is formed on the surface of the underlayer 47 also serving as the lower electrode.
1, a ferromagnetic layer 123, a magnetic coupling layer 125 for orthogonal coupling,
It includes a ferromagnetic pinned layer 127, a nonmagnetic tunnel insulating layer 129, a ferromagnetic free layer 131, a second antiferromagnetic layer 133, an insulating layer 135 surrounding the side wall of the tunnel magnetoresistive film, and an upper electrode layer 137. A tunnel current flows between the upper and lower electrodes, and the tunnel resistance changes due to a relative change in the magnetic direction of the ferromagnetic pinned layer 127 and the ferromagnetic free layer 131. The direction of the external magnetic field can be detected from this information. Incidentally, such a tunnel magnetoresistive film forms a cell including both a diode and a transistor on a substrate in addition to a so-called magnetic sensor such as a magnetic head, and a nonvolatile magnetic random access memory (MRAM) in which a plurality of such cells are formed. ) Is also applicable.

A magnetic head assembly using the above-described magnetoresistive element for a magnetic reproducing head and having the same mounted thereon has the following configuration.

The actuator arm has a hole to be fixed to a fixed shaft in the magnetic disk drive, and a suspension is connected to one end of the actuator arm.

At the tip of the suspension, a head slider on which a magnetic head having the magnetoresistive element according to each of the above embodiments and embodiments is mounted. The suspension is provided with lead wires for signal writing and reading, and one end of the lead wire is electrically connected to each electrode of the magnetoresistive head incorporated in the head slider, and the other end of the lead wire is connected to the suspension. It is connected to the electrode pad.

Next, the internal structure of a magnetic disk drive equipped with a magnetic head assembly, which is a kind of the magnetic recording apparatus of the present invention, will be described below.

The magnetic disk is mounted on a spindle, and is rotated by a motor responsive to a control signal from a drive controller. A head slider for recording and reproducing information while the magnetic disk floats is attached to the tip of a thin-film suspension. Here, the head slider has the above-mentioned magnetoresistive effect reproducing head.

When the magnetic disk rotates, the medium facing surface of the head slider is held in a state of floating above the surface of the magnetic disk by a predetermined amount.

The suspension is connected to one end of an actuator arm having a bobbin for holding a drive coil. A voice coil motor, which is a type of linear motor, is provided at the other end of the actuator arm.
The voice coil motor is composed of a drive coil wound around a bobbin of an actuator arm, a permanent magnet opposed to the coil, and a magnetic circuit including an opposed yoke.

The actuator arm is held by ball bearings provided at two positions above and below the fixed shaft, and can be freely rotated and slid by a voice coil motor.

The materials and the like of the layers exemplified in the embodiments and examples described above are not limited to these.

In addition, depending on the method of forming a layer, for example, the sputtering pressure and sputtering temperature in the sputtering step, the processing temperature, the processing atmosphere, and the processing time in the heat treatment step after the film formation, the adjacent layer or the separated layer may be used. It can easily be assumed that diffusion of atoms occurs from. Therefore, even if a film is formed using the exemplified target material by adjusting these manufacturing methods or the like,
Although the diffusion results in a layer containing a different material, even if such a diffusion occurs, the characteristics (ferromagnetic, antiferromagnetic, substantially orthogonal magnetic coupling,
If the spin-dependent scattering is obtained, the effect of the present invention can be sufficiently exhibited.

[0135]

As described above, it is possible to provide an inexpensive and high-performance magnetoresistive element. Further, a thin-film element can be provided, which is suitable for a magnetic reproducing head requiring a narrow gap and a magnetic reproducing apparatus such as a hard disk drive. Further, it is possible to provide a novel magnetic laminate.

[Brief description of the drawings]

FIG. 1 is a perspective sectional view showing a magnetoresistive element according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a history of a heat treatment step in a magnetic field performed in manufacturing the magnetoresistive element of the present invention using the first embodiment as an example.

FIG. 3 is a modified example 1-1 in which leads of the magnetoresistive element according to the first embodiment of the present invention are overlapped with the central active portion of the element.
FIG.

FIG. 4 is a sectional view showing a modified example 1-2 in which the antiferromagnetic layer in contact with the ferromagnetic free layer of the magnetoresistive element according to the first embodiment of the present invention is not bisected in the plane.

FIG. 5 is a cross-sectional view showing Modification 1-3 in which a nonmagnetic layer is inserted between a ferromagnetic free layer and an antiferromagnetic layer in the magnetoresistive element according to the first embodiment of the present invention.

FIG. 6 is a first modification of the magnetoresistive element according to the first embodiment of the present invention in which a ferromagnetic pinned layer has a laminated ferrimagnetic structure
FIG.

FIG. 7 is a sectional view showing a magnetoresistive element according to a second embodiment of the present invention.

FIG. 8 is a sectional view showing a modification of the magnetoresistive element according to the second embodiment of the present invention.

FIG. 9 is a sectional view showing a magnetoresistive element according to a third embodiment of the present invention.

FIG. 10 is a sectional view showing a magnetoresistive element according to a fourth embodiment of the present invention.

FIG. 11 is a sectional view showing a modification of the magnetoresistive element according to the fourth embodiment of the present invention.

FIG. 12 is a diagram showing a magnetization curve and an MR curve of Example 1.

FIG. 13 shows magnetic fields H ₉₀ and M at which the antiparallel state of Example 2 is broken.
It is a figure which shows the oxidation intensity dependence of R.

FIG. 14 shows magnetic fields H ₉₀ and M at which the antiparallel state of Example 4 is broken.
FIG. 4 is a diagram showing the dependence of R on the thickness of Fe before oxidation.

FIG. 15 is a diagram showing an MR curve of Example 5.

FIG. 16 is a schematic perspective view of a yoke type magnetic head.

FIG. 17 is a perspective view showing a relationship between each layer of the magnetoresistance effect element and the yoke in the yoke type magnetic head.

FIG. 18 is a schematic perspective view showing another example of a yoke type magnetic head.

FIG. 19 is a sectional view showing a tunnel effect element of the present invention.

FIG. 20 is a perspective view showing a conventional patterned bias type magnetoresistance effect element.

[Explanation of symbols]

 REFERENCE SIGNS LIST 31 first antiferromagnetic layer 33 first ferromagnetic layer 35 intermediate layer for orthogonal coupling 37 second ferromagnetic layer 39 intermediate nonmagnetic layer 41 third ferromagnetic phase 43 second Antiferromagnetic layer 45 ... lead electrode

Claims (23)

[Claims] A first ferromagnetic layer having a magnetization in a first direction; a magnetic coupling layer formed by laminating the first ferromagnetic layer; and the first ferromagnetic layer via the magnetic coupling layer. A second ferromagnetic layer having a magnetization in a direction substantially orthogonal to the first direction, the second ferromagnetic layer being magnetically coupled to the first ferromagnetic layer by the magnetic coupling layer, the intermediate nonmagnetic layer; A third ferromagnetic layer laminated with the second ferromagnetic layer via an intermediate non-magnetic layer and having a magnetization substantially in the same direction as the first direction in a state where the external magnetic field is zero. Magnetoresistive element. 2. The magnetic coupling layer according to claim 1, wherein the magnetic coupling layer comprises a mixed phase film including two or more oxides of the same metal having different valences, or a laminated film including two or more oxide layers of the same metal having different valences. The magnetoresistance effect element according to claim 1, wherein: A first ferromagnetic layer having a magnetization in a first direction; a mixed phase film containing two or more oxides of the same metal having different valences;
Alternatively, a laminated film including two or more oxide layers of the same metal having different valences is provided, and an insertion layer formed by laminating the first ferromagnetic layer and the first ferromagnetic layer via the insertion layer. A second ferromagnetic layer laminated and formed with a magnetic layer and having a magnetization substantially perpendicular to the first direction; an intermediate nonmagnetic layer; and a second ferromagnetic layer laminated via the intermediate nonmagnetic layer. And a third ferromagnetic layer having a magnetization substantially in the same direction as the first direction when the external magnetic field is zero. 4. A first ferromagnetic layer laminated on the first ferromagnetic layer.
4. The magnetoresistive element according to claim 1, further comprising: an antiferromagnetic layer formed by: and a second antiferromagnetic layer laminated on the third ferromagnetic layer. 5. 5. The oxide having a different valence comprises an oxide of Fe, FeO, Fe ₃ O ₄ , α-Fe ₂ O ₃ , γ-Fe
4. The magnetoresistive element according to claim 2, wherein the element is selected from ₂ O ₃ . 6. The oxide having a different valence comprises an oxide of Cr, and is CrO, Cr ₂ O ₃ , CrO ₂ , Cr ₂ O ₅ , C _2.
3. A material selected from rO ₃ and CrO _5.
Or a magnetoresistive element according to 3. 7. The magnetoresistive element according to claim 2, wherein said oxides having different valences are oxides of Mn, and are selected from MnO and MnO ₂ . 8. The second ferromagnetic layer is a magnetization free layer in which the direction of the magnetization changes in accordance with a change in an external magnetic field, and the third ferromagnetic layer is a magnetic free layer of the second ferromagnetic layer. 8. The magnetoresistive element according to claim 1, wherein the pinned layer is a pinned layer in which the magnetization direction does not substantially change in an external magnetic field in which the magnetization direction changes. 9. The third ferromagnetic layer is a magnetization free layer in which the direction of the magnetization changes in accordance with a change in an external magnetic field, and the second ferromagnetic layer is formed of the third ferromagnetic layer. 2. A magnetization fixed layer in which the magnetization direction does not substantially change in an external magnetic field in which the magnetization direction changes.
8. The magnetoresistive element according to any one of claims 1 to 7. 10. A first antiferromagnetic layer, a first ferromagnetic layer exchange-coupled to the first antiferromagnetic layer, wherein the first ferromagnetic layer has a magnetization in a first direction, and A magnetic coupling layer laminated with the first ferromagnetic layer; a magnetic coupling layer laminated with the first ferromagnetic layer via the magnetic coupling layer; and a magnetic coupling with the first ferromagnetic layer by the magnetic coupling layer. A second ferromagnetic layer having a magnetization in a direction substantially perpendicular to the first direction, an intermediate nonmagnetic layer, and the second ferromagnetic layer laminated via the intermediate nonmagnetic layer. A magnetoresistive element including a third ferromagnetic layer having a magnetization substantially in the same direction as the first direction in a zero state; and a second antiferromagnetic layer exchange-coupled to the third ferromagnetic layer. A magnetoresistive head. 11. The magnetic coupling layer according to claim 1, wherein the magnetic coupling layer includes a mixed phase film including two or more kinds of oxides of the same metal having different valences, or a laminated film including two or more oxide layers of the same metal having different valences. The magnetoresistive head according to claim 10, wherein: 12. A first ferromagnetic layer having a magnetization in a first direction, a mixed phase film containing two or more oxides of the same metal having different valences,
Alternatively, the semiconductor device includes a laminated film in which two or more oxide layers of the same metal having different valences are laminated, and the first ferromagnetic layer and the insertion layer laminated and formed; A second ferromagnetic layer having a magnetization in a direction substantially orthogonal to the first direction, an intermediate nonmagnetic layer, and the second ferromagnetic layer via the intermediate nonmagnetic layer. And a third ferromagnetic layer having a magnetization substantially in the same direction as the first direction when the external magnetic field is zero. 13. The oxide having a different valence comprises an oxide of Fe, FeO, Fe ₃ O ₄ , αFe ₂ O ₃ , γFe ₂
12. The method according to claim 11, wherein the element is selected from O _3.
3. The magnetoresistive head according to 2. 14. The oxide having a different valence comprises an oxide of Cr, wherein CrO, Cr ₂ O ₃ , CrO ₂ , Cr ₂ O ₅ ,
CrO _3, the magnetoresistive head according to claim 11 or 12, wherein the selected from CrO _5. 15. The magnetoresistive head according to claim 11, wherein said oxides having different valences are oxides of Mn, and are selected from MnO and MnO ₂ . 16. The second ferromagnetic layer is a magnetization free layer in which the direction of the magnetization changes in accordance with a change in an external magnetic field, and the third ferromagnetic layer is formed of the second ferromagnetic layer. 11. The pinned layer, wherein the magnetization direction does not substantially change in an external magnetic field in which the magnetization direction changes.
16. The magnetoresistive effect head according to any one of items 15 to 15. 17. The third ferromagnetic layer is a magnetization free layer in which the direction of the magnetization changes in accordance with a change in an external magnetic field, and the second ferromagnetic layer is formed of the third ferromagnetic layer. 16. The magnetoresistive head according to claim 10, wherein the fixed layer is a magnetization fixed layer in which the magnetization direction does not substantially change in an external magnetic field in which the magnetization direction changes. 18. A medium facing surface at one end, wherein said magnetoresistive element is disposed at a distance from said medium facing surface, and disposed between said medium facing surface and said magnetoresistive effect element. 18. The magnetoresistive head according to claim 10, further comprising a magnetic yoke for expanding an external magnetic field and guiding the external magnetic field to the magnetoresistive element. 19. A magnetic recording medium, a magnetoresistive head for reproducing magnetic information recorded on the magnetic recording medium, wherein a first ferromagnetic layer having a first direction of magnetization; A mixed phase film containing two or more oxides having different numbers,
Alternatively, there is provided a laminated film in which two or more oxide layers of the same metal having different valences are laminated, wherein the first ferromagnetic layer and the insertion layer laminated and formed; A second ferromagnetic layer having a magnetization in a direction substantially orthogonal to the first direction, an intermediate nonmagnetic layer, and the second ferromagnetic layer via the intermediate nonmagnetic layer. And a third ferromagnetic layer having a magnetization substantially in the same direction as the first direction in a state where the external magnetic field is zero. 20. A first ferromagnetic layer having a magnetization in a first direction, a second ferromagnetic layer having a second magnetization in a direction substantially orthogonal to the magnetization in the first direction, and the first and second ferromagnetic layers. An inter-layer film formed between two ferromagnetic layers, wherein the multi-phase film includes two or more oxides of the same metal having different valences, or includes two or more oxide layers of the same metal having different valences. A magnetic laminated body comprising: an interlayer film having a laminated film. 21. The oxide having a different valence comprises an oxide of Fe, FeO, Fe ₃ O ₄ , α-Fe ₂ O ₃ , γ-F
magnetic multilayer structure according to claim 20, wherein the selected from e ₂ O _3. 22. The oxide having a different valence is composed of an oxide of Cr, such as CrO, Cr ₂ O ₃ , CrO ₂ , Cr ₂ O ₅ ,
CrO _3, magnetic multilayer structure according to claim 20, wherein a is selected from CrO _5. 23. The magnetic laminate according to claim 20, wherein the oxides having different valences are oxides of Mn, and are selected from MnO and MnO ₂ .