JPH11330585A - Control of magnetization, magnetically functional element, rocord of information, information recording element and variable resistance element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the generation of crosstalk, which accompanies a scale down of a magnetically functional element, and the reduction in the coercive force of the element by a method wherein the state of magnetic coupling of a fixed magnetic layer with a moving magnetic layer is changed by making to flow a current through the conductor layer of a laminate to control the direction of magnetization of the moving magnetic layer. SOLUTION: A magnetically functional element 10 is provided with a fixed magnetic layer 12 formed on a glass substrate 11, a conductor layer 13 formed on the layer 12, electrodes 14 and 15 connected with both ends of the layer 13 and a moving magnetic layer 17 formed on the layer 13 via an insulating layer 16. The layer 13 consists of a material having a conductivity and controls the state of magnetic coupling of the layer 12 with the layer 17. By making to flow a current through the layer 13 via the electrodes 14 and 15, the state of the mutual exchange action between the layers 12 and 17 is changed and the direction of magnetization of the layer 17 can be controlled. Accordingly, the generation of crosstalk, which accompanies a scale down of the element 10, and the reduction in the coercive force of the element 10 can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for controlling magnetization of a magnetic material. Further, the present invention relates to a magnetic functional element using a magnetic material. Further, the present invention relates to an information recording method and an information recording element for recording information by controlling the magnetization of a magnetic material. The present invention also relates to a variable resistance element that controls electric resistance by controlling magnetization of a magnetic body.

[0002]

2. Description of the Related Art An element utilizing a magnetic material is attractive in two points as compared with a semiconductor device. First,
Since a conductive metal can be used as an element of the element, a high carrier density and a low resistance value can be realized. Therefore, an element using a magnetic material is expected to be suitable for miniaturization and high integration. Second, there is a possibility that the bistability of the magnetization direction of the magnetic material can be used for a nonvolatile memory. That is, if the bistability of the magnetization direction of the magnetic material is used, it is expected that a solid-state nonvolatile memory in which stored information is not lost even if the power of the circuit is turned off.

A solid-state non-volatile memory in which stored information is not lost even when the power of a circuit is turned off is expected to be put to practical use in various fields as an ultimate power-saving memory. Specifically, for example, a solid-state nonvolatile memory consumes no power when inactive, and is therefore expected as a key technology for reducing the capacity and weight of a battery in a portable electronic information device or the like. Also, with the rise of the satellite media business, the demand for solid-state nonvolatile memories is high as that for supporting activities of satellites in the shadow of the earth where solar cells cannot be used.

[0004] Elements using a magnetic material include:
(1) non-volatility, (2) no degradation due to repetition, (3) high-speed writing is possible,
There are advantages such as (4) suitable for miniaturization and high density, and (5) excellent radiation resistance. Less than,
These advantages will be described.

(1) As in the case of a magnetic recording medium such as a magnetic tape or a magnetic disk having non-volatility, the magnetic material itself has a bistability (bist
information), the information written as the magnetization direction is maintained even when the driving force is lost.

(2) No Deterioration Due to Repetition A ferroelectric memory (F-RAM: Ferroelectric Random Access Memory) using a ferroelectric material exhibiting bistability like a magnetic material
Have also been proposed as candidates for solid-state nonvolatile memories.
In the F-RAM, the memory state is rewritten by reversing the spontaneous dielectric polarization. However, the inversion of spontaneous dielectric polarization corresponding to the rewriting of the memory state
Since ion migration in the crystal lattice is involved, if rewriting is repeated over a million times, crystal defects develop. For this reason, in the F-RAM, there is a problem that the element life cannot be exceeded due to the fatigue of the material. On the other hand, since the magnetization reversal of the magnetic material does not involve ion movement or the like, the element using the magnetic material is not limited to the fatigue of the material,
Rewriting can be repeated almost infinitely.

(3) High-speed writing is possible The speed of magnetization reversal of the magnetic material is very fast, about 1 ns or less. Therefore, high-speed writing can be performed by utilizing the high switching speed.

(4) Magnetic alloys suitable for miniaturization and high density The magnetic properties of the magnetic alloy can be variously changed by selecting the composition and the structure. Therefore, in the element using the magnetic material, the degree of freedom in design is extremely high. In an element using a magnetic material, for example, a magnetic alloy having conductivity can be used. When a magnetic alloy having conductivity is used, the current density in the device can be increased as compared with the case where a semiconductor is used, so that it is possible to further reduce the size and density of the semiconductor device.

As an element utilizing such characteristics, for example, a spin transistor has been proposed as described in the Journal of the Japan Society of Applied Magnetics, Vol. 19, 684 (1995). In a spin transistor, as shown in FIG.
The magnetic material E forms an emitter, the magnetic material C forms a collector, and the nonmagnetic material B forms a base. In the spin transistor having such a configuration, an output voltage depending on the magnetization direction of the magnetic bodies C and E is generated due to the polarization density of the magnetic bodies C and E seeping into the non-magnetic body B. Although the spin transistor shown in FIG. 18 has a structure in which the output voltage depends on the magnetization directions of the magnetic materials C and E, the magnetization direction is changed by changing the magnetization current pulse P To supply the current pulse P for magnetization.
Are applied to the magnetic materials C and E.

(5) Excellent radiation resistance In a device such as a D-RAM (Dynamic Random Access Memory), which has a memory state formed by charging an electric capacity, discharge occurs when ionizing radiation passes through the device. , The memory information is lost. On the other hand, since the magnetization direction of the magnetic body is not disturbed by ionizing radiation, the element using the magnetic body has excellent radiation resistance. Therefore, an element using a magnetic material is particularly useful in applications requiring high radiation resistance, such as a communication satellite. Actually, a magnetic bubble memory, which is one of the memories using a magnetic material, has already been used as a memory mounted on a communication satellite and has many achievements.

[0011]

As described above, the element using the magnetic material has various advantages, but also has some problems. In the following, a problem in an element using a magnetic material will be described.
A description will be given using a RAM (Magnetic Random Access Memory) as an example. The problems described below are all caused by applying a magnetic field to the storage carrier for writing.

(1) Crosstalk occurs In the conventional M-RAM, writing to the memory is performed by applying a magnetic field. However, since the magnetic field is a long-distance force, it is selected when the storage carriers are integrated at a high density. A non-negligible effect is also exerted on the area adjacent to the record carrier, and crosstalk occurs. To prevent this, for example, "ZG
Wang, et al., IEEE Trans Magn., Mag33, 4498 (1997) "also reports a design example of a memory cell having a magnetic field shielding structure, but has a drawback that the structure becomes complicated.

(2) Coercive force decreases with miniaturization In the conventional M-RAM, the generation of a write magnetic field depends on the current. However, the current density i [A / m ² ] that can be carried by the conductive wire depends on the material. There are certain limits. Therefore, as the design rule becomes finer and the diameter of the conductive wire becomes smaller, the upper limit of the available current decreases.

Here, assuming that the diameter of the conductor is D [m], the magnetic field strength H [A / m] at a position separated by a distance L [m] from the center of the conductor is expressed by the following equation (1). Is done.

[0015] ^{H = (πiD 2/4)} / (2πL) ··· (1) conductors and the distance between the centers of the storage carrier, since no such that much smaller than D, L = When D is set, the magnetic field intensity H [A / m] applied to the record carrier is expressed by the following equation (2).

[0016] ^{H = (πiD 2/4)} / (2πL) = iD / 8 ··· (2) Further, the allowable current density ^{i = 10 7 [A / cm} 2] = 10 11 [A / m
² ] and D '[μm] = D [m] × 10 ⁶ , the magnetic field intensity H [A / m] applied to the record carrier is represented by the following equation (3).

H = 12,500 × D ′ [A / m] = 156 × D ′ [Oe] (3) As described above, the magnetic material, which is the storage carrier, is arranged closer to the center of the conducting wire by miniaturization. Even if the effect that the record carrier becomes closer to the magnetic field generation source is taken into account, the maximum magnetic field that can be used is reduced in proportion to the design rule.

On the other hand, the coercive force of the storage carrier must be designed so that the magnetization reversal is achieved by a magnetic field applied from the outside. Therefore, when the magnetic field that can be applied to the record carrier decreases with miniaturization, it is necessary to reduce the coercive force of the record carrier accordingly. That is, in the M-RAM, it is necessary to reduce the coercive force of the record carrier with miniaturization. However, if the coercive force of the record carrier becomes too small, the reliability is reduced. This is a serious problem particularly for a memory for a portable electronic device which is often used in an environment where a disturbance magnetic field is applied from the surroundings.

Incidentally, the above-mentioned problem is caused by applying a magnetic field from the outside in order to reverse the magnetization of the storage carrier, and is not limited to the M-RAM. For example, a similar problem occurs in a spin transistor as shown in FIG. The spin transistor realizes the function of changing the output depending on the magnetization direction of the element component. However, the input operation (that is, “means for changing the magnetization direction of the magnetic element involved in determining the output”) is performed by M -As in the case of the RAM, the magnetic field is applied from a nearby current. Therefore, the above two problems pointed out for the M-RAM also exist in the spin transistor.

The present invention has been proposed in view of the above-described conventional circumstances, and provides a magnetization control method capable of avoiding problems such as generation of crosstalk and reduction of coercive force due to miniaturization. It is intended to provide. Another object of the present invention is to provide a magnetic function element, an information recording method, an information recording element, and a variable resistance element that employ such a magnetization control method.

[0021]

According to the magnetization control method of the present invention, a conductor layer and a plurality of magnetic layers are laminated so that a conductor layer containing a conductive material is located between the magnetic layers. To form a laminate. Then, in the magnetization control method according to the present invention, a current is passed through the conductor layer of the laminate to change the magnetic coupling state between the magnetic layers, thereby controlling the magnetization direction of the magnetic layer.

In the magnetization control method, for example, a composite material containing both a single-phase substance exhibiting magnetic order and a non-magnetic substance may be used for the conductor layer. A laminated thin film or a composition modulation film in which a magnetic composition region and a nonmagnetic composition region are alternately formed may be used, or a ferromagnetic composition region and a nonmagnetic composition region may be mixed three-dimensionally. A structure having a different structure may be used.

In the above-described magnetization control method, a layer made of a material having a higher electric resistance than the conductor layer may be provided as an upper layer and a lower layer of the conductor layer. When a layer made of a material having a higher electric resistance than the conductor layer is provided in the upper and lower layers of the conductor layer, the current concentrates on the conductor layer when a current flows through the laminate. It will be.

Further, the magnetic functional element according to the present invention is a laminate comprising a conductor layer and a plurality of magnetic layers laminated such that a conductor layer containing a conductive material is located between the magnetic layers. Is provided. Then, by passing a current through the conductive layer of the laminate, the magnetic coupling state between the magnetic layers is changed, and the magnetization direction of the magnetic layer is controlled. In this magnetic function element, an output corresponding to the magnetization state of the magnetic layer is performed by using a magneto-optical effect such as a magneto-optical Kerr effect and a Faraday effect.

In the magnetic function element, the conductor layer may be made of, for example, a composite material containing both a substance exhibiting magnetic order in a single phase and a nonmagnetic substance. It may be composed of a laminated thin film or a composition modulation film in which regions of a ferromagnetic composition and regions of a nonmagnetic composition are alternately formed. It may have a structure that is dimensionally mixed.

Further, the magnetic function element may include a layer made of a material having higher electric resistance than the conductor layer, as an upper layer and a lower layer of the conductor layer. In the case where a layer made of a material having a higher electric resistance than the conductor layer is provided in the upper layer and the lower layer of the conductor layer, the current concentrates on the conductor layer when a current flows through the laminate. Will be done.

Further, in the information recording method according to the present invention, a laminate in which a conductor layer and a plurality of magnetic layers are laminated so that a conductor layer containing a conductive material is located between the magnetic layers. Is configured. In the method recording method according to the present invention, a current is applied to the conductor layer of the laminate to change the magnetic coupling state between the magnetic layers, thereby controlling the magnetization direction of the magnetic layer, and controlling the magnetization of the magnetic layer. Depending on the direction, binary or more multi-level recording is performed.

In the information recording method, the conductor layer may be made of, for example, a composite material containing both a single-phase substance exhibiting magnetic order and a non-magnetic substance. A laminated thin film or a composition modulation film in which a magnetic composition region and a nonmagnetic composition region are alternately formed may be used, or a ferromagnetic composition region and a nonmagnetic composition region may be mixed three-dimensionally. A structure having a different structure may be used.

In the information recording method, a layer made of a material having a higher electric resistance than the conductor layer may be provided on the upper and lower layers of the conductor layer. When a layer made of a material having a higher electric resistance than the conductor layer is provided in the upper and lower layers of the conductor layer, the current concentrates on the conductor layer when a current flows through the laminate. It will be.

Further, the information recording element according to the present invention is a laminate comprising a conductor layer and a plurality of magnetic layers laminated such that a conductor layer containing a conductive material is located between the magnetic layers. Is provided. Then, by passing a current through the conductive layer of the laminate, the magnetic coupling state between the magnetic layers is changed, the magnetization direction of the magnetic layer is controlled, and the magnetization direction of the magnetic layer is controlled.
Performs multi-level recording of binary or higher. In this information recording element, recorded information is read out by detecting the direction of magnetization of the magnetic layer using a magneto-optical effect such as a magneto-optical Kerr effect or a Faraday effect.

In the information recording element, the conductor layer may be made of, for example, a composite material containing both a substance exhibiting magnetic order in a single phase and a nonmagnetic substance. It may be composed of a laminated thin film or a composition modulation film in which regions of a ferromagnetic composition and regions of a nonmagnetic composition are alternately formed. It may have a structure that is dimensionally mixed.

Further, the information recording element may include a layer made of a material having higher electric resistance than the conductor layer, as an upper layer and a lower layer of the conductor layer. In the case where a layer made of a material having a higher electric resistance than the conductor layer is provided in the upper layer and the lower layer of the conductor layer, the current concentrates on the conductor layer when a current flows through the laminate. Will be done.

The variable resistance element according to the present invention has a first resistance
, A conductive layer, a second magnetic layer, a non-magnetic layer, and a third magnetic layer.
Then, by passing a current through the conductor layer of the laminate, the magnetic coupling state between the first magnetic layer and the second magnetic layer is changed to control the magnetization direction of the second magnetic layer. In addition, by controlling the magnetization direction of the second magnetic layer, the electric resistance of the path leading to the second magnetic layer, the non-magnetic layer, and the third magnetic layer is controlled.

In the variable resistance element, the conductive layer may be made of, for example, a composite material containing both a single-phase magnetically ordered substance and a non-magnetic substance. It may be composed of a laminated thin film or a composition modulation film in which regions of a ferromagnetic composition and regions of a nonmagnetic composition are alternately formed. It may have a structure that is dimensionally mixed.

Further, the variable resistance element may include a layer made of a material having higher electric resistance than the conductor layer, as an upper layer and a lower layer of the conductor layer. In the case where a layer made of a material having a higher electric resistance than the conductor layer is provided in the upper layer and the lower layer of the conductor layer, the current concentrates on the conductor layer when a current flows through the laminate. Will be done.

[0036]

Embodiments of the present invention will be described below in detail with reference to the drawings.

1. Principle of the present invention In the present invention, a magnetic interaction (exchange interaction: exchange interaction) in a solid is performed without depending on an external magnetic field application.
Using action) as a driving force, magnetization reversal occurs in the magnetic layer that is a component of the element. Here, the magnetic layer in which the magnetization reversal occurs can be called a “movable magnetic layer” because its magnetization direction changes, or can be called a “record carrier” assuming an information recording element.

The exchange interaction is none other than the origin of aligning the magnetic moment of an atom in a ferromagnetic material in one direction. Further, as shown in FIG. 1, when the magnetic material A and the magnetic material B are in contact with each other, the contact interface S
Exchange interaction works through. Further, as shown in FIG. 2, even if the magnetic material A and the magnetic material B are not in direct contact and the intermediate layer C exists between the magnetic material A and the magnetic material B, the magnetic material A Interaction between the magnetic material B and the magnetic material B may propagate through the intermediate layer C. Here, when the intermediate layer C is a magnetic material, the exchange interaction naturally propagates, but the intermediate layer C is made of Cu, which does not exhibit magnetism by itself.
It has been confirmed that even in the case of a nonmagnetic metal such as Au or a semiconductor such as Si or Ge, the exchange interaction propagates through the intermediate layer C. A theory (such as the RKKY model) that explains the origin of such exchange interaction propagation has also been proposed.

In the present invention, the magnetization direction of the magnetic material is controlled by utilizing such exchange interaction. Hereinafter, a method of controlling the magnetization direction using the exchange interaction will be described with a specific example.

As shown in FIG. 2, the magnetic material A and the magnetic material B
Are not in direct contact with each other, and the intermediate layer C exists between the magnetic material A and the magnetic material B. Here, the magnetic material A is
It is assumed that the material is a soft magnetic material whose magnetization direction is easily changed. Also,
It is assumed that the magnetic body B is a permanent magnet having a fixed magnetization direction. The intermediate layer C between the magnetic material A and the magnetic material B is a ferromagnetic material, but is a material having a low Curie temperature Tc at which the magnetic layer loses magnetic order at a higher temperature.

At this time, in an environment in which the temperature is higher than the Curie temperature Tc of the intermediate layer C, there is no magnetic order in the intermediate layer C. The magnetization of the body A is oriented in an arbitrary direction by an external field. When the temperature is lowered to a temperature lower than the Curie temperature Tc as it is, magnetic order is generated in the intermediate layer C, and an interaction acts to align the magnetization directions of the magnetic substances A and B via the intermediate layer C. . At this time, since the magnetic body B is a permanent magnet, the magnetization direction of the magnetic body A, which has been oriented in an arbitrary direction until then, changes so as to be aligned with the magnetization direction of the magnetic body B. The change in the magnetization direction of the magnetic body A is not caused by an external magnetic field but caused by an exchange interaction in a solid.

In the magnetization control method according to the present invention, the magnetization direction of the magnetic material is controlled using such exchange interaction as a driving force. Note that, in the present invention, the exchange interaction is controlled by an electrical input, instead of being changed by the environmental temperature as in the above-described example.

The magnetic function element according to the present invention is an element utilizing an operation of changing the magnetization direction using such exchange interaction as a driving force. In other words, the magnetic function element according to the present invention is an element composed of a multilayer structure of a plurality of thin films containing a magnetic material and terminals for electrical input / output, and the operation of the element depends on the magnetization direction of the ferromagnetic material. Includes the process of changing. The change in the magnetization direction of the ferromagnetic material is not caused by the change in the external magnetic field applied to the ferromagnetic material, but is based on the change in the exchange interaction in the solid.

As described above, in the magnetization control method according to the present invention, the exchange direction in the solid is used as the driving force to control the magnetization direction of the magnetic material. An information recording element can be configured.
When configuring the information recording element, a magnetic material A having a coercive force of several tens Oe, whose magnetization direction is easily changed moderately, is used as a record carrier, and a magnetic material B made of a permanent magnet is written on the record carrier. Used as a drive source for Then, depending on the direction of magnetization of the magnetic material A, binary or multi-level recording is performed.

Here, a magnetic material A having a coercive force of several tens of Oe whose magnetization direction is easily changed moderately is used as a record carrier, and a magnetic material B made of a permanent magnet is used as a drive source for a write operation on the record carrier. The exchange interaction in the used information recording element will be described.

It is assumed that the magnetic bodies A and B are laminated films. In the laminated film, the contact surface is larger than the volume of the magnetic material, and the exchange interaction can be transmitted effectively.
In the following description, the layer of the magnetic material A having a coercive force of several tens of Oe in which the magnetization direction is likely to change appropriately will be referred to as a record carrier layer because it is used as a record carrier. Further, the layer of the magnetic body B made of a permanent magnet is fixed so that the magnetization direction is directed to a fixed direction, and is therefore referred to as a fixed magnetic layer. Since the information recording element according to the present invention is considered to be a small element, the storage carrier layer has a single magnetic domain structure.

Generally, the potential energy _Uex due to the exchange interaction between the two layers is proportional to the area S of the interface. _Assuming that the magnetization direction of the record carrier layer is θ and the magnetization direction of the fixed magnetic layer is θ _flx , the potential energy U _ex due to the exchange interaction between the two layers is expressed by the following equation (1)
-1).

U _ex = −S · J · cos (θ−θ _flx ) (1-1) On the other hand, in the external magnetic field H, the potential energy (Zeeman Energy) of the external magnetic field H )
Has U _Z. This potential energy U _Z is obtained by setting the saturation magnetic flux density of the record carrier layer to M _S , the thickness to t, and the external magnetic field H
When the direction and theta _H, is expressed by the following equation (1-2).

[0049] As shown in _{U Z = -S · t · M} S · H · cos (θ-θ H) ··· (1-2) above formula (1-1) and (1-2), and potential energy U _ex by exchange interaction, the potential energy U _Z by external magnetic field, and the same shape. That is, the exchange interaction also has the function of changing the magnetization direction of the record carrier layer in the same manner as the external magnetic field. Therefore, the magnitude of the exchange interaction can be treated as the magnetic field conversion value _Hex . That is, if θ _flx and θ _H are made equal and U _ex and U _Z are made equal, the following equation (1-3) is established.

−S · J · cos (θ−θ _H ) = − S · t · M _S · H _ex · cos (θ−θ _H ) (1-3) Therefore, the magnitude of the exchange interaction the value H _ex converted to a magnetic field can be represented by the following formula (1-4).

H _ex = J / (M _s · t) (1-4) Then, the coercive force H _c of the record carrier layer becomes the above-mentioned magnetic field conversion value H
If it is smaller than _ex, it is possible to cause magnetization reversal by exchange interaction.

Conventionally, a magnetic field generated by passing a current through a conductor is applied to a record carrier. However, the magnetic field intensity H that can be applied to a record carrier by passing a current through a conductor is as described above. Is represented by equation (3). That is, when a magnetic field is applied to the record carrier by passing a current through the conductor, the magnitude of the magnetic field that can be used is proportional to the diameter D ′ of the conductor.

H = 12,500 × D ′ [A / m] = 156 × D ′ [Oe] (3) On the other hand, as can be seen from the above equation (1-4), the effect of magnetization reversal due to exchange interaction Does not depend on the area of the interface. Therefore, in the course of the technological trend of miniaturizing the element size, the action of the magnetization reversal due to the exchange interaction of the present invention always exceeds the action of the conventional magnetic field application.

For example, as the value of the exchange interaction, J =
0.05 mJ / m ² , thickness t of the record carrier layer = 10 nm,
When the saturation magnetic flux density M _s = 1T of the record carrier layer and these values are substituted into the above equation (1-4), the magnetic field conversion value H _ex = 5000 A / m = 63 Oe of the exchange interaction is obtained. On the other hand, the magnetic field strength H represented by the above equation (3) is 63 Oe when the diameter D ′ of the conductor is 0.4 μm.

That is, the magnetization control method according to the present invention
An element size that is more effective than a method using a magnetic field generated by flowing a current through a conductive wire is in a submicron region. In view of recent technological trends, it is certain that the design rule will eventually be on the order of submicrons in magnetic memories and the like. Therefore, it is clear that the magnetization control method according to the present invention will eventually surpass the method using a magnetic field generated by flowing a current through a conductive wire.

Here, regarding the relationship between the cell size L of the information recording element and the drive magnetic field H that can be used for driving the record carrier, a current magnetic field method utilizing a magnetic field generated by passing a current through a conductor, FIG. 3 shows a comparison with an exchange coupling method using exchange interaction in a solid. In the current magnetic field method, the diameter D 'of the conducting wire was assumed to be 0.8 times the cell size. As shown in FIG. 3, in the current magnetic field method, the magnetic field that can be applied from the conductor decreases as the cell size decreases. On the other hand, since the exchange interaction in the laminated structure does not depend on the cell size, the exchange coupling method becomes advantageous as the miniaturization progresses.

As described above, the magnetic field conversion value H _ex of the exchange interaction does not depend on the cell size. Therefore, if the magnetization of the record carrier is controlled using the exchange interaction, even if the miniaturization proceeds, it is possible to use a large magnetic thin film coercivity H _c as a record carrier. Specifically, as can be seen from FIG. 3, it is possible to use a magnetic thin film having a coercive force of several tens [Oe] or more as a record carrier even when the cell size is extremely small. Incidentally, by lowering the value of the saturation magnetic flux density M _s,
It is also possible to further increase the coercivity of the record carrier.
Moreover, the effect of the magnetization reversal when the present invention is applied is based on the exchange interaction occurring only between the materials in contact with each other, so that the problem of crosstalk to neighboring elements can be avoided.

2. Specific Example of Element Next, an element according to the present invention utilizing the above principle will be described in detail with reference to specific examples.

2-1 Magnetic Function Element FIGS. 4 and 5 show an example of a magnetic function element to which the present invention is applied. As shown in FIGS. 4 and 5, the magnetic function element 10 includes a fixed magnetic layer 12 formed on a glass substrate 11.
A conductor layer 13 formed on the fixed magnetic layer 12,
Electrodes 14, 1 connected to both ends of conductor layer 13, respectively.
5 and a movable magnetic layer 17 formed on the conductor layer 13 with an insulating layer 16 interposed therebetween.

Here, the fixed magnetic layer 12 is made of an oxide magnetic material having a high coercive force, and has a fixed magnetization direction. That is, the fixed magnetic layer 12 is referred to as a “fixed magnetic layer” in the sense that the magnetization direction does not change during the element operation and is in a fixed state. On the other hand, the movable magnetic layer 17 is made of a magnetic material having a small coercive force.
In this example, the magnetization direction of the movable magnetic layer 17 can be controlled. That is, the movable magnetic layer 17 is called a “movable magnetic layer” in the sense that the magnetization direction is variable during element operation.

The conductor layer 13 is made of a material having conductivity, and is a layer for controlling a magnetic coupling state between the fixed magnetic layer 12 and the movable magnetic layer 17. That is, the conductor layer 13 is, in other words, the fixed magnetic layer 12 and the movable magnetic layer 1.
It can also be said that it is a coupling control layer for controlling the magnetic coupling state with the layer 7.

In the magnetic function element 10, the conductor layer 13
By passing a current through the electrodes 14 and 15 through the electrodes 14 and 15, the state of the exchange interaction between the fixed magnetic layer 12 and the movable magnetic layer 17 can be changed, and the magnetization direction of the movable magnetic layer 17 can be controlled. It has become. In other words, the magnetic function element 1
At 0, the exchange interaction can be controlled by an electrical input to control the magnetization direction of the element element.

In the magnetic function element 10, the fixed magnetic layer 12 made of an oxide material having high electric resistance is formed below the conductor layer 13, and the fixed magnetic layer 12 is formed above the conductor layer 13. An insulating layer 16 having a high resistance is formed. As described above, the upper and lower layers of the conductor layer 13 include:
By forming a layer made of a material having high electric resistance, when a current is supplied from the electrodes 14 and 15, the current is effectively concentrated on the conductor layer 13. Therefore,
The magnetic function element 10 can be driven with a low current.

The magnetic function element 10 is an element having a function of controlling the magnetization direction of the movable magnetic layer 17, but its use is not particularly limited. For example, as described later, it can be used as an electro-optic modulator, can be used as an information recording element, or can be used as a variable resistance element or an amplification element. .

2-1-1 Manufacturing Method of Magnetic Function Element The present inventor used a five-source magnetron sputtering apparatus to
The magnetic function element 10 was actually manufactured. Hereinafter, the manufacturing procedure will be described.

(I) Formation of Fixed Magnetic Layer First, a fixed magnetic layer 12 made of a cobalt ferrite thin film was formed on a glass substrate 11 made of BK-7. Specifically, a vertical (y-direction) 20 μm × horizontal (x-direction) 220 μm is placed on the glass substrate 11 heated to 250 ° C.
The cobalt ferrite thin film was deposited through a first mask having a rectangular opening. Where cobalt
The ferrite thin film was deposited using a sintered target of CoFe ₂ O ₄ and RF-magnetron sputtering at a deposition rate of 0.3 nm / s to a thickness of 300 nm. At this time, the sputtering gas is Ar
To which 10% of O ₂ is added.
sccm and the sputter gas pressure was 3 mTorr.

(Ii) Formation of Conductor Layer Next, on the fixed magnetic layer 12, a conductor layer 13 composed of a multilayer film in which a Cr film and an Fe—Ag film were repeatedly laminated was formed. Specifically, the fixed magnetic layer 12 was formed while simultaneously sputtering two Fe-Ag mosaic targets (six Ag-shaped Ag plates having a central angle of 15 ° on an Fe target) and a Cr target. Glass substrate 11
However, a multilayer film in which a Cr film and an Fe—Ag film were repeatedly laminated was deposited at room temperature so as to stay alternately on each target. At this time, the thickness of each Cr film was 0.9 nm, and the thickness of each Fe-Ag film was 1.5 nm. The order of deposition is such that Fe-
The deposition is started from the Ag film, and is half-deposited for 16 periods,
-The Ag film was set on the top.

(Iii) Formation of Insulating Layer Next, an insulating layer 16 made of aluminum oxide was formed on the conductor layer 13. More specifically, first, 20 μm × 2 μm so as to overlap the center of the already deposited pattern.
After disposing a Mo mask having a square opening of 0 μm, an Al thin film having a thickness of 0.8 nm was deposited. Thereafter, the Al thin film was subjected to plasma oxidation using the substrate etching function of the sputtering apparatus to form an insulating layer 16. In addition, Al
The plasma oxidation of the thin film was performed under an atmosphere in which 5% O ₂ was added to Ar at a gas pressure of 10 mTorr.

(Iv) Formation of Movable Magnetic Layer Next, a movable magnetic layer 17 made of a Ni ₇₈ Fe ₂₂ alloy thin film was formed on the insulating layer 16. Specifically, 3 μm × 3 μm so as to overlap the center of the already deposited pattern.
After arranging a Mo mask having a square opening of m,
While heating the glass substrate 11 to 160 ° C., a thickness of 10 n
m of Ni ₇₈ Fe ₂₂ alloy thin film was deposited. At this time, N
The i ₇₈ Fe ₂₂ alloy thin film is deposited while applying a magnetic field of 50 Oe in a direction (y direction) parallel to the vertical side of the pattern in order to impart magnetic anisotropy to the Ni ₇₈ Fe ₂₂ alloy thin film. Was.

(V) Formation of Electrode Next, on both ends of the conductor layer 13, an electrode 1 made of Au was formed.
4, 15 were formed. Specifically, an Au thin film having a length of 100 μm × width of 100 μm and a thickness of 200 nm was deposited so as to overlap on both ends of the conductor layer 13 (that is, to overlap the left and right ends of the already deposited pattern).

(Vi) Magnetization of Pinned Magnetic Layer Lastly, at room temperature, a magnetic field of 2 kOe is applied using an electromagnet in a direction (x direction) parallel to the horizontal side of the pattern, The magnetization direction was aligned with the + x direction to complete the magnetic function element 10 as shown in FIGS.

2-1-2 Confirmation of Exchange Interaction Next, an external magnetic field is applied to the magnetic functional element 10 manufactured as described above, the magnetization history of the movable magnetic layer 17 is observed, and the exchange interaction is confirmed . The result of confirming the existence will be described.

For observing the magnetization history of the movable magnetic layer 17, the magneto-optical Kerr effect (MOK) which is proportional to the magnetization of the material surface layer is used.
E: Magneto-Optical Kerr Effect) was used. That is, as shown in FIG. 6, a magneto-optical Kerr effect measuring device is provided for each pair in the xz plane and the yz plane, and the Kerr rotation angle proportional to the magnetization component in the x direction is set. , And a Kerr rotation angle proportional to the magnetization component in the y direction.

Here, as shown in FIG. 6, the magneto-optical Kerr effect measuring device for measuring the Kerr rotation angle in the x direction includes a semiconductor laser 21x for emitting a visible light laser having a wavelength of 670 nm, a polarizer 22x, A first lens 23x, a second lens 24x, an analyzer 25x, and a photodetector 26x
Are provided with an optical system arranged in the xz plane. Then, the magneto-optical Kerr effect measuring apparatus irradiates the movable magnetic layer 17 of the magnetic function element 10 with the laser light emitted from the semiconductor laser 21x via the polarizer 22x and the first lens 23x. Reflected light to the second lens 24x
Then, the Kerr rotation angle proportional to the magnetization component in the x direction is measured by detecting the photodetector 26x via the analyzer 25x. Here, the incident angle of the laser light irradiating the movable magnetic layer 17 of the magnetic function element 10 and the polarization plane of the laser light are:
It is set so that only the magneto-optical Kerr effect due to the movable magnetic layer 17 can be efficiently detected.

On the other hand, a magneto-optical Kerr effect measuring device for measuring the Kerr rotation angle in the y-direction has a wavelength of 6 as shown in FIG.
Semiconductor laser 2 that emits 70 nm visible light laser
1y, the polarizer 22y, the first lens 23y, and the second
The lens 24y, the analyzer 25y, and the photodetector 26y are provided with an optical system arranged in the yz plane. Then, the magneto-optical Kerr effect measuring device irradiates the movable magnetic layer 17 of the magnetic function element 10 with the laser light emitted from the semiconductor laser 21y via the polarizer 22y and the first lens 23y. The reflected light is transmitted to the second lens 24y.
Then, the Kerr rotation angle proportional to the magnetization component in the y direction is measured by detecting the photodetector 26y via the analyzer 25y. Here, the incident angle of the laser light irradiating the movable magnetic layer 17 of the magnetic function element 10 and the polarization plane of the laser light are:
It is set so that only the magneto-optical Kerr effect due to the movable magnetic layer 17 can be efficiently detected.

In order to observe the magnetization history of the movable magnetic layer 17, the size and direction of the magnetic function element 1 were changed.
An external magnetic field was applied to 0. Here, the application of the external magnetic field to the magnetic function element 10 was performed by a pair of coils 27 and 28 arranged so as to sandwich the magnetic function element 10 from both sides as shown in FIG. And the coils 27, 2
8, the magnitude and direction of the magnetic field applied to the magnetic function element 10 were changed by changing the position of the coils 27 and 28.

By the way, a sample vibration type magnetometer (V
When the in-plane magnetization curve of the pinned magnetic layer 12 was measured by SM: Vibrating Sample Magnetometer, the magnetization curve had a good square shape and the coercive force was 1060 Oe. Therefore, the observation of the magnetization history of the movable magnetic layer 17 by the magneto-optical Kerr effect is performed by applying an applied magnetic field strength of ± 500 O so as not to change the magnetization state of the fixed magnetic layer 12 magnetized in the + x direction.
e. The observation of the magnetization history of the movable magnetic layer 17 includes the magnetization history in the x direction when the current is not supplied to the conductor layer 13 and the magnetization history in the y direction when the current is not supplied to the conductor layer 13. History was performed in four ways: a magnetization history in the x direction when a current was supplied to the conductor layer 13, and a magnetization history in the y direction when a current was supplied to the conductor layer 13.

First, the magnetization history of the movable magnetic layer 17 when current was not supplied to the conductor layer 13 was observed. The observation result of the magnetization history in the x direction is shown on the upper left side of FIG. 7, and the observation result of the magnetization history in the y direction is shown on the upper right side of FIG. The magnetization history in the x direction shown on the upper left side of FIG. 7 has a shape in which a left-right symmetric hysteresis curve is shifted to the left side. This indicates that the movable magnetic layer receives a bias that is easily magnetized in the + x direction. On the other hand, as can be seen from the magnetization history in the y direction shown on the right side of the upper part of FIG.
The residual magnetization in the direction is very small. From these facts, it can be understood that the magnetization direction of the movable magnetic layer 17 is substantially in the x direction at zero magnetic field.

Next, the magnetization history of the movable magnetic layer 17 was observed while supplying a current of 1.2 mA to the conductor layer 13.
The observation result of the magnetization history in the x direction is shown on the lower left side of FIG. 7, and the observation result of the magnetization history in the y direction is shown on the lower right side of FIG. As can be seen from these observation results, when a current was supplied to the conductor layer 13, the movable magnetic layer 17 exhibited characteristics of easy magnetization in the y direction.

The current supply was stopped and the movable magnetic layer 1
When the magnetization history of No. 7 was observed, the movable magnetic layer 17 again showed the magnetization history as shown in the upper part of FIG. Therefore, it was found that the change in the magnetic properties depending on whether the current was supplied to the conductor layer 17 was reversible.

Here, for comparison, N.sub.
FIG. 8 shows the results obtained by forming only the i-Fe alloy thin film and observing the magnetization history of the Ni-Fe alloy thin film. The sample for this observation was obtained by using Ni-Fe under an environment in which a magnetic field was applied in the y-direction in the same manner as when forming the movable magnetic layer 17.
It was prepared by depositing an alloy thin film directly on a glass substrate. As shown in FIG. 8, the magnetization curve in the y direction of the Ni—Fe alloy thin film manufactured under the environment where the magnetic field was applied in the y direction has a large coercive force and a large residual magnetization.
It can be seen that the alloy thin film has magnetic anisotropy that is easily magnetized in the y direction.

As can be seen from FIG. 8, the Ni—Fe alloy thin film deposited in the magnetic field has an easy axis of magnetization in the direction of the applied magnetic field. Therefore, the magnetic function element 1
The zero movable magnetic layer 17 alone should easily be magnetized in the y-direction, and the characteristics of the observation results shown in FIG. 7 are considered to reflect the influence from the underlayer.

As described above, when no current is supplied to the conductor layer 13, the movable magnetic layer 17 receives a bias that tends to direct magnetization in the + x direction at zero magnetic field.
This suggests that a ferromagnetic interaction propagates from the underlayer magnetized in the + x direction to try to align the magnetization directions in the same direction. On the other hand, when a current is supplied to the conductor layer 13, the movable magnetic layer 17 shows characteristics similar to the observation results of the comparative sample shown in FIG. 8, and the characteristics of the movable magnetic layer itself are more remarkable. Is appearing. From this, it is understood that the influence of the underlying layer is weakened by passing a current through the conductive layer 13.

From the above observation results, the movable magnetic layer 17 and
The fixed magnetic layer 1 serving as an underlayer of the movable magnetic layer 17
It has been confirmed that an exchange interaction exists between the first and second conductive layers 13 and that the exchange interaction is weakened by supplying a current to the conductor layer 13.

2-1-3 Verification of Switch Operation The ratio of the magnetization component in each direction in the zero magnetic field state is read from FIG. 7, and the direction of the magnetization vector of the movable magnetic layer 17 estimated from this is shown in FIG. It became so. And
From FIG. 9, it was found that the absolute value of the magnetization of the movable magnetic layer 17 did not change, and the angle formed with the x direction was switched between about 20 ° and about 85 °. Therefore, it was actually verified that the magnetization vector of the movable magnetic layer 17 is switched between the two directions by turning on / off the current supplied to the conductor layer 13.

For verification of the switch operation, two sets of magneto-optical Kerr effect measuring devices as shown in FIG. 6 are used simultaneously, and the Kerr rotation angle in the x direction, which is proportional to the magnetization component of the movable magnetic layer 17 in the x direction, and While monitoring the Kerr rotation angle in the y direction, which is proportional to the y direction magnetization component of the movable magnetic layer 17,
3 was performed by switching the ON / OFF of the current to be supplied.

FIG. 10 shows the results. In FIG. 10, θ _Kx indicates the Kerr rotation angle in the x direction, θ _Ky indicates the Kerr rotation angle in the y direction, and current I indicates the current supplied to the conductor layer 13. . As shown in FIG. 10, a change in the magnetization direction of the movable magnetic layer 17 in synchronization with the ON / OFF operation of the current supplied to the conductor layer 13 is recognized, and only while the current is input to the conductor layer 13. "Momentary" switch operation in which the output changes was verified.

When a current is supplied to the conductor layer 13, the magnetization vector of the movable magnetic layer 17 changes so as to increase the angle formed between the movable magnetic layer 17 and the direction in which the current flows. Angle range was not changed.
This also indicates that the role of the magnetic field generated by the current in changing the magnetization direction of the movable magnetic layer 17 is small, and the driving force of the switching operation is a change in the exchange interaction.

In the magnetic function element 10, since the upper and lower layers of the conductor layer 13 are made of oxides having an electric resistance much higher than that of the conductor layer 13, the electrodes 14 and
The current of 1.2 mA supplied via the capacitor 15 flows almost only to the conductor layer 13. Then, in the magnetic function element 10, the conductor layer 13 having a width of 20 μm has
The portion related to the switching operation of the movable magnetic layer 17 of 3 μm in width is only the central 3 μm. Therefore, net 0.
This means that the switch operation has been achieved with a current of 18 mA.

As described above, in the magnetic function element 10,
The switching operation can be performed with a very small current.
For example, in an M-RAM, there is a report that the current flowing through a conductor is reduced to about 1 mA in order to control the magnetization of a record carrier. However, in the magnetic function element 10, the switching is performed with a much smaller current. The operation can be performed. Moreover, in the method of the present invention in which the magnetization is controlled by the exchange interaction, when the cell size is further reduced, the current required for the switching operation is further reduced. When a current of 1.2 mA is supplied to the conductor layer 13, the current density is about 1.56 × 10 ⁹ A / m ^2.
It is. This value is approximately the same as the current density of the current flowing through the conductor for controlling the magnetization of the record carrier in an existing M-RAM or the like.

2-1-4 Function of Conductor Layer In the magnetic function element 10, a multilayer film in which a Cr film and an Fe—Ag film are repeatedly laminated is exchanged between the fixed magnetic layer 12 and the movable magnetic layer 17. It was used as the conductor layer 13 for controlling the interaction. Hereinafter, a mechanism for controlling the exchange interaction between the fixed magnetic layer 12 and the movable magnetic layer 17 by the conductive layer 13 will be described.

In a multilayer film in which a Cr film and an Fe film are laminated,
It is known that when the thickness of the Cr film is appropriately selected (about 0.7 nm), antiferromagnetic coupling occurs in which the magnetizations of the Fe films on both sides thereof are in parallel and opposite directions. Even when an Fe-Ag film is used instead of the Fe film, similar magnetic coupling occurs with the Cr film interposed. However, instead of the Fe film, Fe
-When an Ag film is used, the strength of the magnetic coupling throughout the entire multilayer film is reduced due to the inclusion of Ag.

In the magnetic function element 10, Cr
Since there are an even number of films, ferromagnetic coupling occurs between the lowermost Fe-Ag film and the uppermost Fe-Ag film so that their magnetic moments are parallel and aligned in the same direction.

Here, the first deposited Fe—Ag film is a fixed magnetic layer 12 made of a cobalt ferrite thin film.
And ferromagnetically coupled. On the other hand, the last deposited Fe-
An insulating layer 16 made of aluminum oxide is formed on the Ag film.
However, since the insulating layer 16 is extremely thin, it has many pinholes. Therefore, the uppermost Fe—Ag film is formed through the pinholes through the movable magnetic layer 1 made of a Ni—Fe alloy thin film formed thereon.
7 and ferromagnetically. Then, when the coupling from the fixed magnetic layer 12 to the movable magnetic layer 17 is traced in order, it can be seen that ferromagnetic coupling occurs between the fixed magnetic layer 12 and the movable magnetic layer 17. This is consistent with the result from the magnetic characteristics shown in the upper part of FIG.

In the magnetic function element 10, when a current is supplied to the conductor layer 13, the magnetic coupling between the fixed magnetic layer 12 and the movable magnetic layer 17 is weakened. It is difficult to narrow down the cause of the strength attenuation to one. However, the mechanism can be estimated. That is, when a current is supplied to the conductor layer 13, the current causes excessive electron scattering in the conductor layer 13, and spins are carried in a direction perpendicular to the film surface of the stacked film, and between the upper and lower magnetic layers. It is believed that the electrons that mediate exchange coupling are disturbed and magnetic coupling is weakened. In addition, since the temperature rise due to the current weakens the magnetic order in the conductor layer, magnetic coupling is broken by the temperature rise due to the current, and as a result, the strength of the magnetic coupling mediated by the entire conductor layer is increased. Is thought to be attenuated.

Here, an example of the conductor layer 13 is shown in FIG. The conductor layer 13A shown in FIG.
a and an intermediate layer 13 disposed between the magnetic layers 13a.
b are laminated. The conductor layer 1 shown in FIG.
3A, the magnetic layer 13a has four layers and the intermediate layer 13b has three layers. However, in the conductor layer 13 used in the magnetic function element 10, the magnetic layer 13a has 17 layers, and the intermediate layer 13b has three layers.
Has 16 layers. However, the number of these layers is not particularly limited, and can be appropriately changed according to a desired magnetic coupling state.

The conductor layer 1 of the magnetic function element 10
In No. 3, an Fe—Ag film was used as the magnetic layer 13a and a Cr film was used as the intermediate layer 13b, but the material of the magnetic layer 13a and the intermediate layer 13b is not limited to these.

For example, the magnetic layer 13a includes Fe, Co,
A ferromagnetic metal such as Ni or an alloy obtained by diluting the ferromagnetic metal with a non-magnetic metal can be used. On the other hand, the intermediate layer 13b includes Ti, V, Mn, Cu, Zr, Nb,
Mo, Ru, Rh, Pd, Ag, Hf, Ta, W, R
Most metals such as e, Ir, Pt, and Au can be used. Further, Cr, which is itself antiferromagnetic at room temperature as used in the above-described conductor layer 13, can be used as the intermediate layer 13b as a matter of course. In the conductor layer 13A having such a laminated structure, whether the obtained magnetic coupling is ferromagnetic or antiferromagnetic, or the strength of the magnetic coupling is as follows.
For example, various changes can be made depending on the type of the magnetic layer 13a, the thickness of the intermediate layer 13b, the number of the magnetic layers 13a and the intermediate layers 13b, and the like.

The conductive layer 13 used in the magnetic function element 10 may have any function as long as it has a function of changing the manner of propagation of magnetic interaction in a solid in accordance with an electric input. Therefore, the conductor layer 13 may be made of, for example, a composite material containing both a single-phase magnetically ordered substance and a non-magnetic substance. In this case, there is an advantage that the conductor layer 13 can be formed without using a multi-source sputtering apparatus, and the formation of the conductor layer 13 is easy.

The conductor layer 13 may be formed of a laminated thin film or a composition modulation film in which regions of a ferromagnetic composition and regions of a nonmagnetic composition are alternately formed. In this case, since the structure of the conductor layer 13 can be easily controlled, there is an advantage that reproducibility of characteristics is high. Moreover, it is easy to adjust the material design and the characteristics by changing the film thickness and the lamination cycle. The conductor layer 13 shown in FIG.
A is included in this.

The conductor layer 13 may have a structure in which a region having a ferromagnetic composition and a region having a nonmagnetic composition are three-dimensionally mixed. In this case, since there are many magnetic coupling paths having different strengths, it is possible to gradually reduce the magnetic coupling by cutting the weak coupling in order. Therefore, such a structure is particularly suitable for a case where an analog operation is performed, for example, as in a variable resistance element described later.

Here, FIG. 12 shows an example of the conductor layer 13 having a structure in which a region having a ferromagnetic composition and a region having a nonmagnetic composition are three-dimensionally mixed. Conductor layer 13 shown in FIG.
B has a fine particle dispersion structure in which the ferromagnetic fine particles 13c are dispersed inside the nonmagnetic material 13d. In the conductive layer 13B having such a fine particle dispersed structure, the magnetic coupling is transmitted between the ferromagnetic fine particles 13c like a stepping stone, and as a result, the magnetic coupling with the fixed magnetic layer 12 disposed above and below the conductive layer 13B is movable. The magnetic layer 17 is magnetically coupled.

At this time, the magnetic coupling between the ferromagnetic fine particles is very weak, and the magnetic coupling is apt to be broken by excessive electron scattering or temperature rise when a current flows. That is, in the case of the conductive layer 13B having the fine particle dispersion structure, the magnetic coupling between the fixed magnetic layer 12 and the movable magnetic layer 17 disposed above and below the conductive layer 13B depends on the weak magnetic coupling between the ferromagnetic fine particles. In addition, macro magnetic coupling is likely to be broken by a current flowing through the conductor layer 13B.

In the conductive layer 13B having the fine particle dispersed structure, the material of the ferromagnetic fine particles 13c may be any of the same materials as those exemplified as the material of the magnetic layer 13a constituting the conductive layer 13A having the laminated structure. Can also be used. Further, as the material of the nonmagnetic material 13d in which the ferromagnetic fine particles 13c are dispersed, any of the same materials as those exemplified as the material of the intermediate layer 13b constituting the conductor layer 13A having the laminated structure can be used. .

By the way, such a fine particle dispersion structure is
It can also be used as one element of a laminated structure. actually,
In the magnetic function element 10, the conductor layer 13 has Fe—Ag
Although a film was used, since this Fe-Ag film is made of a non-solid solution two-phase mixed material, it can be said that, more precisely, it has a fine particle dispersed structure.

As the conductor layer 13 used in the magnetic function element 10, not only a layer in which two or more phases coexist, but also a single-phase ferrimagnetic substance in a state near a compensation point can be used. It is. In a single-phase ferrimagnetic material in the state near the compensation point, macroscopic magnetic characteristics are significantly changed by an external stimulus. Therefore, by using a single-phase ferrimagnetic material near the compensation point for the conductor layer 13, the fixed magnetic layer 12
It is possible to control the magnetic coupling state between the magnetic layer and the movable magnetic layer 17 or to directly modulate the magnetic bias on the movable magnetic layer 17.

2-1-5 Output Method In the experiment described above, the result of the switching operation of the magnetization direction of the movable magnetic layer 17 was optically detected using the magneto-optical Kerr effect. In other words, this means that the magnetic function element 10 operates as an electro-optic modulator. However, the result of the switching operation of the magnetization direction of the movable magnetic layer 17 can be obtained as an electrical output.

When the result of the switching operation of the magnetization direction of the movable magnetic layer 17 is obtained as an electrical output, for example, as shown in FIG.
As shown in FIG. 3, a spacer layer 30 made of a non-magnetic metal and a magnetic layer 31 made of a magnetic metal fixed so that the magnetization direction is directed to a fixed direction are arranged on the movable magnetic layer 17. Thus, the spacer layer 3 is formed on the movable magnetic layer 17.
By disposing 0 and the magnetic layer 31, it is possible to detect a change in the magnetization direction of the movable magnetic layer 17 as a resistance change by the spin pulp operation of the movable magnetic layer 17, the spacer layer 30, and the magnetic layer 31.

More specifically, for example, as shown in FIG.
The output circuit 3 connects the movable magnetic layer 17 and the magnetic layer 31.
Constituting No. 2. At this time, the resistance changes depending on the angle between the magnetization direction of the movable magnetic layer 17 and the magnetization direction of the magnetic layer 31, and the magnitude of the output current flowing through the output circuit changes.

Instead of utilizing the spin pulp operation, the result of the switching operation of the magnetization direction of the movable magnetic layer 17 can be detected by utilizing the tunnel magnetoresistance effect. When using the tunnel magnetoresistance effect,
An insulator is used for the spacer layer 30. Spacer layer 30
When an insulator is used, the magnitude of the output current flowing through the output circuit 32 changes due to the tunnel magnetoresistance effect.

As another method, four terminals may be appropriately connected to the movable magnetic layer 17 and a voltage output may be obtained by the Hall effect depending on the magnetization direction of the movable magnetic layer 17 using the four terminals. It is possible.

2-2 Write-once Information Recording Element Next, a write-once information recording element utilizing modulation of exchange interaction by current will be described.

In the following description, the operation of causing the magnetization direction of the movable magnetic layer to be directed in a certain direction is referred to as a driving operation. A layer that exerts a driving action on the movable magnetic layer is called a driving layer. That is, in the following description, portions corresponding to the fixed magnetic layer 12 and the conductor layer 13 in the above-described magnetic function element 10 are collectively referred to as a drive layer.

2-2-1 FIG. 14 shows an example of an information recording element in which writing can be performed only once by utilizing the modulation of the exchange interaction by the positive logic drive type information recording element current. FIG. 14 is a schematic diagram for explaining the driving principle of the information recording element, and omits the wiring and the like of the output circuit and the input circuit.

As shown in FIG. 14, this information recording element 4
0 indicates that a movable magnetic layer 42 having uniaxial magnetic anisotropy is formed on the drive layer 41, and binary recording can be performed depending on the direction of magnetization of the movable magnetic layer 42.
In FIG. 14, an arrow M1 indicates a magnetization direction of the movable magnetic layer 42, and an arrow A1 indicates a driving action acting on the movable magnetic layer 42 from the driving layer 41.

This information recording element 40 has a movable magnetic layer 42
When the magnetization direction is changed, the driving action A1 acts on the movable magnetic layer 42 from the driving layer 41, that is, a so-called "positive logic drive type" element. Hereinafter, the driving principle of the information recording element 40 will be described.

In this information recording element 40, FIG.
In the reset state, as shown in FIG.
Is set to be opposite to the direction of the driving action A1 from the driving layer 41. In the example of FIG. 14, the direction of the driving action A1 is leftward, and in the reset state, the magnetization direction M1 of the movable magnetic layer 42 is rightward. In this reset state, the driving layer 4
A current is supplied to the conductive layer constituting the driving layer 41 so that the driving action A1 does not act on the movable magnetic layer 42 from 1.

Then, when the magnetization direction M1 of the movable magnetic layer 42 is changed to the "ON state" for writing information, the supply of the current to the conductor layer constituting the drive layer 41 is stopped. As a result, an exchange interaction acts between the driving layer 41 and the movable magnetic layer 42, and the driving layer 41
The driving action A1 works.

At this time, the drive layer 41 is moved from the movable magnetic layer 42
Is greater than the coercive force of the movable magnetic layer 42. If the driving action A1 is made to exceed the coercive force of the movable magnetic layer 42, the magnetization of the movable magnetic layer 42 is reversed when it is turned on, as shown in FIG. The magnetization direction M1 of the layer 42 is aligned with the direction of the driving action A1. That is, in the example of FIG. 14, when the ON state is established, the magnetization direction M1 of the movable magnetic layer 42 is reversed so as to be leftward.

Thereafter, the supply of current to the conductor layer forming the drive layer 41 is restarted, and the drive layer 41
Even if the driving action A1 does not act on 2, the magnetization direction M1 of the inverted movable magnetic layer 42 is maintained as shown in FIG. 14C due to the uniaxial magnetic anisotropy. . That is, even in a state where the driving action A1 does not act on the movable magnetic layer 42 from the driving layer 41, FIG.
As shown in (c), the set state in which the magnetization direction M1 of the movable magnetic layer 42 is reversed is maintained.

As described above, in the information recording element 40, the ON of the current supply to the conductor layer forming the drive layer 41 is turned on.
By switching between / OFF, the magnetization direction M1 of the movable magnetic layer 42 can be reversed, and binary recording can be performed depending on the magnetization direction of the movable magnetic layer 42. However, this information recording element 40
Must maintain the current supply to the conductive layer constituting the drive layer 41 in order to maintain the reset state,
Not a non-volatile memory.

The inventor of the present invention has adopted the information recording element 40 described above as having the magnetic function element 1 shown in FIGS.
0, a fixed magnetic layer made of a cobalt ferrite thin film and magnetized in the -x direction, a conductor layer made of a multilayer film in which a Cr film and an Fe-Ag film are repeatedly laminated, and an insulating material made of aluminum oxide An element in which a layer and a movable magnetic layer made of a Ni—Fe alloy thin film having an easy axis of magnetization in the x-axis direction were formed on a glass substrate was actually manufactured.

Then, ON / O of current supply to the conductor layer is performed.
The change in the magnetization direction of the movable magnetic layer when the FF was switched was examined by measuring the magneto-optical Kerr effect.
Specifically, first, in a state where a current is supplied to the conductor layer, +
A magnetic field of 40 Oe was applied in the x direction, and the magnetization of the movable magnetic layer was aligned in the + x direction. Thereafter, when the applied magnetic field was removed while the current was supplied to the conductor layer, the magnetization of the movable magnetic layer was maintained in the + x direction.
A magnetization reversal in the direction was observed.

As described above, the current supply to the conductive layer is turned on.
By switching between / OFF, it was confirmed that the magnetization direction of the movable magnetic layer can be changed, and writing can be performed once. However, the switching operation of the magnetization direction of the movable magnetic layer here changes the angle between the magnetization direction of the movable magnetic layer and the x direction between about 20 ° and about 85 ° as shown in FIG. Not switch operation, but parallel /
The switch operation was between antiparallel.

FIG. 15 shows another example of an information recording element in which writing can be performed only once using the modulation of the exchange interaction by the current of the negative logic drive type information recording element . FIG. 15 is a schematic diagram for explaining the driving principle of the information recording element, similarly to FIG. 14, and omits the wiring and the like of the output circuit and the input circuit.

In this information recording element 50, as shown in FIG. 15, a movable magnetic layer 52 having uniaxial magnetic anisotropy is formed on a driving layer 51, and further, the driving layer 51 is formed on the movable magnetic layer 52. An antiferromagnetic layer 53 is formed to act on the movable magnetic layer 52 with a driving action opposite to the driving action from
Depending on the direction of magnetization of the movable magnetic layer 52, binary recording can be performed. In FIG. 15, an arrow A1 indicates a driving action acting on the movable magnetic layer 52 from the driving layer 51, and an arrow A2 indicates a driving action acting on the movable magnetic layer 52 from the antiferromagnetic layer 53. The arrow M1 indicates the magnetization direction of the movable magnetic layer 52.

The information recording element 50 changes the magnetization direction M1 of the movable magnetic layer 52 when the driving action A1 does not act on the movable magnetic layer 52 from the drive layer 51. Type "element. Hereinafter, the driving principle of the information recording element 50 will be described.

In this information recording element 50, FIG.
In the reset state, as shown in FIG.
Is set to be the same as the direction of the driving action A1 from the driving layer 51. In the example of FIG. 15, the direction of the driving action A1 is rightward, and in the reset state, the magnetization direction M1 of the movable magnetic layer 52 is rightward.

In the information recording element 50, in the reset state, no current is supplied to the conductive layer constituting the driving layer 51. Therefore, in the reset state,
The driving action A1 from the driving layer 51 acts on the movable magnetic layer 52. However, in the information recording element 50, as shown by an arrow A2, a driving action A2 in a direction opposite to the driving action A1 from the driving layer 51 acts on the movable magnetic layer 52 from the antiferromagnetic layer 53. Driving action A1 from layer 51
Are offset by the driving action A2 from the antiferromagnetic layer 53. However, since the movable magnetic layer 52 has uniaxial magnetic anisotropy, the magnetization direction M1 of the movable magnetic layer 52 depends on the driving action A1 from the driving layer 51 and the driving action A2 from the antiferromagnetic layer 53. Instead, the direction that was initially magnetized is maintained as it is.

Then, when the magnetization direction M1 of the movable magnetic layer 52 is changed to the “ON state” for writing information, a current is supplied to the conductive layer constituting the drive layer 51.
As a result, the exchange interaction between the driving layer 51 and the movable magnetic layer 52 is weakened, and the driving action A1 from the driving layer 51 to the movable magnetic layer 52 does not work. At this time, the driving action A2 acting on the movable magnetic layer 52 from the antiferromagnetic layer 53
Has a size exceeding the coercive force of the movable magnetic layer 52. If the driving action A2 from the antiferromagnetic layer 53 is made to exceed the coercive force of the movable magnetic layer 52, as shown in FIG.
When the driving action A1 for No. 2 stops working, the magnetization of the movable magnetic layer 52 is reversed, and the magnetization direction M1 of the movable magnetic layer 52 is aligned with the direction of the driving action A2 from the antiferromagnetic layer 53. That is, in the example of FIG. 15, when the ON state is established, the magnetization direction M1 of the movable magnetic layer 52 is reversed so as to be leftward.

Thereafter, even if the current supply to the conductive layer constituting the drive layer 51 is stopped and the drive action A1 acts on the movable magnetic layer 52 from the drive layer 51, the same as in the reset state. The driving action A1 from the driving layer 51 is canceled by the driving action A2 from the antiferromagnetic layer 53.
Since the movable magnetic layer 52 has uniaxial magnetic anisotropy, the magnetization direction M1 of the inverted movable magnetic layer 52 is
As shown in FIG. 5 (c), it is held as it is. That is, the current supply to the conductor layer forming the drive layer 51 is stopped, and the drive action A is applied from the drive layer 51 to the movable magnetic layer 52.
Even in the state where 1 is working, as shown in FIG. 15C, the set state where the magnetization direction M1 of the movable magnetic layer 52 is reversed is maintained.

As described above, in the information recording element 50, by switching ON / OFF of the current supply to the conductor layer 52 constituting the drive layer 51, the movable magnetic layer 52
Can be reversed.
Depending on the direction of magnetization of the movable magnetic layer 52, binary recording can be performed. Moreover, the information recording element 5
0 means that there is no need to supply a current to the conductive layer constituting the drive layer 51 in order to maintain the reset state or the set state. That is, the information recording element 50 is a nonvolatile memory.

The present inventor has made the information recording element 50 described above a magnetic functional element 1 shown in FIG. 4 and FIG.
0, a fixed magnetic layer composed of a cobalt ferrite thin film and magnetized in the + x direction, a conductor layer composed of a multilayer film in which a Cr film and an Fe-Ag film are repeatedly laminated, and an insulating layer composed of aluminum oxide And a movable magnetic layer made of a Ni—Fe alloy thin film having an easy axis of magnetization in the x-axis direction, formed on a glass substrate, and further placed on the movable magnetic layer in the −x direction with respect to the movable magnetic layer. Rh-M that works the driving action of
An element having an antiferromagnetic layer made of an n film was actually manufactured.

Then, ON / O of the current supply to the conductor layer is performed.
The change in the magnetization direction of the movable magnetic layer when the FF was switched was examined by measuring the magneto-optical Kerr effect.
Specifically, first, a magnetic field is applied in the + x direction while no current is supplied to the conductor layer, and the magnetization of the movable magnetic layer is increased by +
Aligned in x direction. Thereafter, when the applied magnetic field was removed, the magnetization of the movable magnetic layer was maintained in the + x direction.
When current was supplied to the conductor layer, magnetization reversal in the -x direction was observed.

As described above, the ON of the current supply to the conductor layer is performed.
By switching between / OFF, it was confirmed that the magnetization direction of the movable magnetic layer can be changed, and writing can be performed once. However, the switching operation of the magnetization direction of the movable magnetic layer here changes the angle between the magnetization direction of the movable magnetic layer and the x direction between about 20 ° and about 85 ° as shown in FIG. It was not a switch operation but a switch operation from the + x direction to the -x direction.

Also, ON / OF of the current supply to the conductor layer
Once the magnetization of the movable magnetic layer was inverted by switching F, the inverted state was maintained even after the current supply was stopped. That is, it was confirmed that the element in which the antiferromagnetic layer was formed on the movable magnetic layer operated as a nonvolatile memory.

2-3 An example of a rewritable information recording element utilizing the modulation of the exchange interaction by the rewritable information recording element current is shown in FIG. FIG.
FIG. 6 is a schematic diagram for explaining the driving principle of the information recording element, similarly to FIGS. 14 and 15, and omits the wiring and the like of the output circuit and the input circuit.

In this information recording element 60, as shown in FIG. 16, a movable magnetic layer 61 having uniaxial magnetic anisotropy has
Of the movable magnetic layer 61, so that binary recording can be performed depending on the direction of magnetization of the movable magnetic layer 61.

In FIG. 16, arrow A1 indicates the first arrow.
The arrow A2 indicates the driving action acting on the movable magnetic layer 61 from the second driving layer 63 to the movable magnetic layer 61, and the arrow M indicates the driving action acting on the movable magnetic layer 61 from the second driving layer 63.
Reference numeral 1 denotes the magnetization direction of the movable magnetic layer 61.

When the direction along the easy axis of the movable magnetic layer 61 is defined as the x direction, the first drive layer 62 sets the magnetization direction M1 of the movable magnetic layer 61 in the + x direction (the rightward direction in FIG. 16). ), The driving action A1 is applied to the movable magnetic layer 61. On the other hand, the second driving layer 6
3 indicates that the magnetization direction M1 of the movable magnetic layer 61 is in the −x direction (FIG. 1).
6 (the leftward direction in FIG. 6), the driving action A2 is applied to the movable magnetic layer 61.

In this information recording element 60, if the driving action A1 from the first driving layer 62 to the movable magnetic layer 61 is not activated, the driving action A2 from the second driving layer 63 to the movable magnetic layer 61 causes the movable element A2 to move. The magnetization direction M1 of the magnetic layer 61 is
−x direction. On the other hand, if the driving action A2 from the second driving layer 63 to the movable magnetic layer 61 is not performed,
Driving action A1 from first driving layer 62 to movable magnetic layer 61
As a result, the magnetization direction M1 of the movable magnetic layer 61 is oriented in the + x direction.

Further, in the information recording element 60, the driving action A1 from the first driving layer 62 to the movable magnetic layer 61 is performed.
When both the driving action A2 from the second driving layer 63 to the movable magnetic layer 61 and the driving action A1 from the first driving layer 62 and the driving action A2 from the second driving layer 63 are performed. The action A2 cancels out, and the magnetization direction M1 of the movable magnetic layer 61 is stabilized by the uniaxial magnetic anisotropy of the movable magnetic layer itself,
The state up to that point is kept as it is.

Hereinafter, the driving principle of the information recording element 60 will be described in more detail.

FIG. 16A shows a state in which the magnetization direction M1 of the movable magnetic layer 61 is kept in the + x direction (right direction in the figure). At this time, no current is supplied to the conductor layer forming the first driving layer 62 and no current is supplied to the conductor layer forming the second driving layer 63. Therefore, the movable magnetic layer 6
1 includes a driving action A1 from the first driving layer 62 and a second driving action A1.
And the driving action A2 from the driving layer 63 works. However, since the direction of the driving action A1 from the first driving layer 62 and the direction of the driving action A2 from the second driving layer 63 are opposite to each other, the driving action A1 from the first driving layer 62 is opposite.
And the driving action A2 from the second driving layer 63 cancels out. Therefore, the magnetization direction M1 of the movable magnetic layer 61 is stabilized by the uniaxial magnetic anisotropy of the movable magnetic layer itself, and the state up to that point (here, the magnetization direction M
1 is in the + x direction).

Next, FIG. 16B shows the movable magnetic layer 61.
Shows the state when the magnetization direction M1 is rewritten from the + x direction (right direction in the figure) to the −x direction (left direction in the figure). At this time, a current is supplied to the conductor layer that forms the first driving layer 62. As a result, the driving action A1 from the first driving layer 62 to the movable magnetic layer 61 does not work. On the other hand, no current is supplied to the conductor layer forming the second drive layer 63.
Therefore, the driving action A2 from the second driving layer 63 acts on the movable magnetic layer 61.

At this time, the driving action A2 acting on the movable magnetic layer 61 from the second drive layer 63 is set to have a magnitude exceeding the coercive force of the movable magnetic layer 61. If the driving action A2 from the second driving layer 63 is made to exceed the coercive force of the movable magnetic layer 61, the driving action A1 from the first driving layer 62 becomes as shown in FIG. When it stops working, the magnetization of the movable magnetic layer 61 is reversed from the + x direction (right direction in the figure) to the -x direction (left direction in the figure), and the magnetization direction M1 of the movable magnetic layer 61 is changed to the second drive layer. It is aligned in the direction of the driving action A2 from 63.

Next, FIG. 16C shows the movable magnetic layer 61.
Is maintained in the -x direction (right direction in the figure). At this time, no current is supplied to the conductor layer forming the first driving layer 62 and no current is supplied to the conductor layer forming the second driving layer 63. Therefore, the driving action A1 from the first driving layer 62 is applied to the movable magnetic layer 61.
And the driving action A2 from the second driving layer 63 works. However, since the direction of the driving action A1 from the first driving layer 62 and the direction of the driving action A2 from the second driving layer 63 are opposite to each other, the driving action A1 from the first driving layer 62 is opposite. And the driving action A2 from the second driving layer 63 cancels out. Therefore, the magnetization direction M1 of the movable magnetic layer 61
Is stabilized by the uniaxial magnetic anisotropy of the movable magnetic layer itself, and the previous state (here, the state in which the magnetization direction M1 of the movable magnetic layer 61 is oriented in the −x direction) is maintained as it is.

Next, FIG. 16D shows the movable magnetic layer 61.
Shows a state in which the magnetization direction M1 is rewritten from the −x direction (left direction in the drawing) to the + x direction (right direction in the drawing). At this time, a current is supplied to the conductor layer forming the second drive layer 63. As a result, the driving action A2 from the second driving layer 63 to the movable magnetic layer 61 does not work. On the other hand, no current is supplied to the conductor layer forming the first drive layer 62.
Therefore, the driving action A1 from the first driving layer 62 acts on the movable magnetic layer 61.

At this time, the driving action A1 acting on the movable magnetic layer 61 from the first driving layer 62 has a magnitude exceeding the coercive force of the movable magnetic layer 61. If the driving action A1 from the first driving layer 62 is made to exceed the coercive force of the movable magnetic layer 61, the driving action A2 from the second driving layer 63 becomes as shown in FIG. When the movable magnetic layer 61 stops operating, the magnetization of the movable magnetic layer 61 is reversed from the −x direction (left direction in the figure) to the + x direction (right direction in the figure), and the magnetization direction M1 of the movable magnetic layer 61 is changed to the first driving layer. The driving action A1 from the direction 62 is aligned.

As described above, in the information recording element 60, ON / OFF of the current supply to the conductor layer forming the first driving layer 62 and the current supply to the conductor layer forming the second driving layer 63 are controlled. By switching the current supply ON / OFF, the magnetization direction M1 of the movable magnetic layer 61 can be reversed, and binary recording can be performed according to the magnetization direction of the movable magnetic layer 61. It has become. Moreover, in the information recording element 60, the magnetization direction M1 of the movable magnetic layer 61 can be repeatedly reversed, and the recorded information can be repeatedly rewritten. Further, the information recording element 60 includes the movable magnetic layer 6.
In order to maintain the magnetization direction M1, the first driving layer 62
It is not necessary to supply a current to the conductive layer forming the second driving layer 63 or the conductive layer forming the second driving layer 63. That is, the information recording element 60 is a nonvolatile memory.

By the way, in the information recording elements 40, 50, 60 described above, the movable magnetic layers 42, 52, 61
A binary recording can be performed by using a magnetic recording medium having uniaxial magnetic anisotropy. However, the movable magnetic layers 42, 52, and 61 may be those having three or more minimum points of anisotropic energy with respect to the direction of magnetization. When the movable magnetic layers 42, 52, and 61 have three or more minimum points of anisotropic energy with respect to the direction of magnetization, one movable magnetic layer may have three or more values. Can be performed.

2-4 FIG. 17 shows an example of the variable resistance element utilizing the modulation of the exchange interaction by the current of the variable resistance element.

The variable resistance element 80 shown in FIG.
(Element in which the result of the switching operation of the magnetization direction of the movable magnetic layer is obtained as an electrical output). That is, the variable resistance element 80
As shown in FIG. 17, a first fixed magnetic layer 81 fixed so that the magnetization direction Ma is oriented in a fixed direction, a conductor layer 82 formed on the fixed magnetic layer 81, and a conductor layer 82 A movable magnetic layer 83 formed thereon, a spacer layer 84 made of a non-magnetic metal formed on the movable magnetic layer 83,
A second fixed magnetic layer 85 made of a magnetic metal and fixed so that the magnetization direction Mb is directed to a fixed direction.

In the variable resistance element 80, the conductor layer 82
, The magnetic coupling state between the first fixed magnetic layer 81 and the movable magnetic layer 83 is changed, and the magnetization direction Mc of the movable magnetic layer 83 is controlled. Here, the conductor layer 8
For 2, it is preferable to use a material in which the degree of change in the magnetic coupling state between the first fixed magnetic layer 71 and the movable magnetic layer 83 with respect to the input current value is relatively gentle. By using a material whose degree of change in the magnetic coupling state is relatively gentle, the magnetization direction Mc of the movable magnetic layer 83 can be changed almost steplessly by current input to the conductor layer 82. .

In order to make the degree of change in the magnetic coupling state relative to the input current value relatively gentle, specifically, for example, a region having a ferromagnetic composition and a region having a non-magnetic composition May be used in a structure in which these regions are mixed three-dimensionally. As described above, in a structure in which the region of the ferromagnetic composition and the region of the nonmagnetic composition are mixed three-dimensionally, there are many magnetic coupling paths having different strengths. By doing so, it is possible to gradually reduce the magnetic coupling. Accordingly, the magnetization direction Mc of the movable magnetic layer 83 can be changed almost steplessly by the current input to the conductor layer 82, and the movable magnetic layer 83 can be operated in an analog manner.

In the variable resistance element 80, the movable magnetic layer 83, the spacer layer 84, and the second fixed magnetic layer 85
A spin valve is constituted by the movable magnetic layer 8.
When the magnetization direction Mc of the third magnetic layer changes, the spin pulp operation of the movable magnetic layer 83, the spacer layer 84, and the second fixed magnetic layer 85 causes the path to reach the movable magnetic layer 83, the spacer layer 84, and the second fixed magnetic layer 85. Changes the electrical resistance of the

That is, in this variable resistance element 80, by passing a current through the conductor layer 82, the first fixed magnetic layer 81
The magnetization direction Mc of the movable magnetic layer 83 can be controlled by changing the magnetic coupling state between the movable magnetic layer 83 and the movable magnetic layer 83. Thus, the magnetization direction Mc of the movable magnetic layer 83 is controlled. By doing so, it is possible to control the electric resistance of the path leading to the movable magnetic layer 83, the spacer layer 84, and the second fixed magnetic layer 85.

This variable resistance element 80 is, for example, as shown in FIG.
By using a circuit configuration as shown in FIG. 1 and setting the spin valve composed of the movable magnetic layer 83, the spacer layer 84, and the second fixed magnetic layer 85 to have an appropriate operating point, it can be used as an analog amplifier. Can also. That is, by adopting a circuit configuration as shown in FIG.
With a small current input to the conductor layer 82, an amplification operation that changes the impedance of the large current circuit on the output side becomes possible.

[0159]

As described above in detail, in the magnetization control method and the information recording method according to the present invention, the magnetization direction of the magnetic layer is controlled by changing the magnetic coupling state between the magnetic layers. Therefore, in controlling the magnetization direction of the magnetic layer, it is possible to avoid problems such as generation of crosstalk and reduction of coercive force due to miniaturization. And
The magnetic function element, the information recording element, and the variable resistance element according to the present invention using such a magnetization control method can avoid problems such as generation of crosstalk and reduction of coercive force even when miniaturization is advanced. . Therefore, according to the present invention, it is possible to realize a magnetic memory or the like with higher integration.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure in which a magnetic body A and a magnetic body B are in contact with each other.

FIG. 2 is a diagram showing a structure in which an intermediate layer C exists between a magnetic body A and a magnetic body B.

FIG. 3 is a diagram showing a relationship between a cell dimension L of an information recording element and a driving magnetic field H that can be used for driving a record carrier.

FIG. 4 is a plan view showing an example of a magnetic function element to which the present invention is applied.

5 is a diagram illustrating an example of a magnetic function element to which the present invention is applied, and is a cross-sectional view taken along line X1-X2 in FIG.

FIG. 6 is a diagram illustrating a method of measuring magnetization components in two orthogonal directions (x direction and y direction).

FIG. 7 is a diagram showing measurement results of magnetization histories of a magnetic functional element in two orthogonal directions (x direction and y direction).

FIG. 8 is a diagram showing a magnetization curve of a Ni—Fe alloy thin film formed on a nonmagnetic substrate.

FIG. 9 is a diagram showing the magnetization direction of the movable magnetic layer of the magnetic function element, showing the magnetization direction when an electric current is supplied to the conductor layer, and the magnetization direction when no electric current is supplied to the conductor layer. FIG. 4 is a diagram showing the magnetization directions of the magnetic field.

FIG. 10 is a diagram illustrating a result of observing a time change of magnetization in two orthogonal directions (x direction and y direction) of the magnetic function element when switching ON / OFF of a current supplied to a conductor layer. .

FIG. 11 is a diagram schematically showing the structure of a conductor layer having a laminated structure.

FIG. 12 is a diagram schematically showing the structure of a conductor layer having a fine particle dispersion structure.

FIG. 13 is a diagram showing the configuration of the magnetic function element and its peripheral circuit when the result of the switching operation of the magnetization direction of the movable magnetic layer is obtained as an electrical output.

FIG. 14 is a schematic diagram for explaining the driving principle of a negative-write drive type information recording element which is a one-time writable type information recording element. FIG. 14 (a) is a view showing a reset state. 14B is a diagram showing an ON state, and FIG. 14C is a diagram showing a set state.

FIG. 15 is a schematic diagram for explaining the driving principle of a positive-write drive type information recording element which is a once-writable information recording element, and FIG. 15A shows a reset state; FIG. 15B shows the ON state, and FIG. 15C shows the set state.

FIG. 16 is a schematic diagram for explaining the driving principle of the rewritable information recording element, and FIG.
FIG. 16B shows a state in which the magnetization direction of the movable magnetic layer is held rightward, FIG. 16B shows a state in which the magnetization direction of the movable magnetic layer is rewritten leftward, and FIG. FIG. 16D shows a state in which the magnetization direction of the layer is held to the left, and FIG. 16D shows a state in which the magnetization direction of the movable magnetic layer is rewritten to the right.

FIG. 17 is a diagram showing an example of a variable resistance element to which the present invention is applied.

FIG. 18 is a diagram showing a configuration of a spin transistor.

[Explanation of symbols]

Reference Signs List 10 magnetic functional element, 11 glass substrate, 12 fixed magnetic layer, 13 conductor layer, 14, 15 electrode,
16 insulating layer, 17 movable magnetic layer

Claims (27)

[Claims] 1. A laminate comprising a conductor layer and a plurality of magnetic layers laminated so that a conductor layer containing a conductive material is located between magnetic layers, A magnetization control method characterized by changing a magnetic coupling state between magnetic layers by passing a current through a conductor layer to control a magnetization direction of the magnetic layer. 2. The magnetization control method according to claim 1, wherein the conductor layer is made of a composite material containing both a single-phase magnetically ordered substance and a non-magnetic substance. 3. The magnetization control method according to claim 1, wherein the conductor layer is formed of a laminated thin film or a composition modulation film in which regions having a ferromagnetic composition and regions having a nonmagnetic composition are alternately formed. 4. The magnetization control method according to claim 1, wherein the conductor layer has a structure in which a region having a ferromagnetic composition and a region having a nonmagnetic composition are mixed three-dimensionally. 5. The magnetization control method according to claim 1, wherein a layer made of a material having a higher electric resistance than the conductor layer is provided as an upper layer and a lower layer of the conductor layer. 6. A laminate comprising a conductor layer and a plurality of magnetic layers laminated so that a conductor layer containing a conductive material is located between magnetic layers, A magnetic function element characterized in that a current flows through a body layer to change a magnetic coupling state between magnetic layers, thereby controlling a magnetization direction of the magnetic layer. 7. The magnetic functional element according to claim 6, wherein an output corresponding to the magnetization state of the magnetic layer is performed using a magneto-optical effect. 8. The magnetic function element according to claim 6, wherein the conductor layer is made of a composite material containing both a substance exhibiting magnetic order in a single phase and a nonmagnetic substance. 9. The magnetic function element according to claim 6, wherein the conductor layer is formed of a laminated thin film or a composition modulation film in which regions of a ferromagnetic composition and regions of a nonmagnetic composition are alternately formed. 10. The magnetic function element according to claim 6, wherein the conductor layer has a structure in which a region having a ferromagnetic composition and a region having a nonmagnetic composition are three-dimensionally mixed. 11. The magnetic function element according to claim 6, wherein a layer made of a material having higher electric resistance than the conductor layer is provided on the upper and lower layers of the conductor layer. 12. A laminate comprising a conductor layer and a plurality of magnetic layers laminated so that a conductor layer containing a material having conductivity is located between the magnetic layers. By passing a current through the conductor layer, the magnetic coupling state between the magnetic layers is changed to control the magnetization direction of the magnetic layer. Depending on the magnetization direction of the magnetic layer, binary or more multi-level recording is performed. An information recording method, characterized in that: 13. The information recording method according to claim 12, wherein the conductor layer is made of a composite material containing both a substance exhibiting magnetic order in a single phase and a nonmagnetic substance. 14. The information recording method according to claim 12, wherein said conductor layer is formed of a laminated thin film or a composition modulation film in which regions of a ferromagnetic composition and regions of a nonmagnetic composition are alternately formed. 15. The information recording method according to claim 12, wherein the conductor layer has a structure in which a region having a ferromagnetic composition and a region having a nonmagnetic composition are three-dimensionally mixed. 16. The information recording method according to claim 12, wherein a layer made of a material having a higher electric resistance than the conductor layer is provided as an upper layer and a lower layer of the conductor layer. 17. A laminate comprising a conductor layer and a plurality of magnetic layers laminated so that a conductor layer containing a conductive material is located between the magnetic layers, By passing a current through the body layer, the magnetic coupling state between the magnetic layers is changed to control the magnetization direction of the magnetic layer. Depending on the magnetization direction of the magnetic layer, binary or more multi-level recording is performed. An information recording element characterized by the above-mentioned. 18. The information recording element according to claim 17, wherein the recorded information is read by detecting the direction of magnetization of the magnetic layer using the magneto-optical effect. 19. The information recording element according to claim 17, wherein the conductor layer is made of a composite material containing both a substance exhibiting magnetic order in a single phase and a nonmagnetic substance. 20. The information recording element according to claim 17, wherein the conductor layer is formed of a laminated thin film or a composition modulation film in which regions of a ferromagnetic composition and regions of a nonmagnetic composition are alternately formed. 21. The information recording element according to claim 17, wherein the conductor layer has a structure in which a region having a ferromagnetic composition and a region having a nonmagnetic composition are three-dimensionally mixed. 22. The information recording element according to claim 17, wherein a layer made of a material having higher electric resistance than the conductor layer is provided on the upper and lower layers of the conductor layer. 23. A laminate comprising a first magnetic layer, a conductor layer, a second magnetic layer, a non-magnetic layer, and a third magnetic layer, wherein the laminate comprises By passing a current through the body layer, the magnetic coupling state between the first magnetic layer and the second magnetic layer is changed to control the magnetization direction of the second magnetic layer,
By controlling the magnetization direction of the magnetic layer, the second magnetic layer,
A variable resistance element which controls electric resistance of a path leading to a nonmagnetic layer and a third magnetic layer. 24. The variable resistance element according to claim 23, wherein the conductor layer is made of a composite material containing both a substance exhibiting magnetic order in a single phase and a nonmagnetic substance. 25. The variable resistance element according to claim 23, wherein the conductor layer is formed of a laminated thin film or a composition modulation film in which regions of a ferromagnetic composition and regions of a nonmagnetic composition are alternately formed. 26. The variable resistance element according to claim 23, wherein the conductor layer has a structure in which a region having a ferromagnetic composition and a region having a nonmagnetic composition are three-dimensionally mixed. 27. The variable resistance element according to claim 23, wherein a layer made of a material having higher electric resistance than the conductor layer is provided on the upper and lower layers of the conductor layer.