JPH11232711A - Magnetic memory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To utilize a multilayer film, where an antiferromagnetic layer, magnetic layer, non-magnetic layer and magnetic layer are laminated in this order, as a magnetic memory. SOLUTION: A memory cell 10 composed of the multilayer film, where an antiferromagnetic layer 15, magnetic layer 14, non-magnetic layer 13 and magnetic layer 12 are laminated in this order, is heated by laser beam 20 and when cooling the memory cell 10, a magnetic field H is impressed. Thus, information is recorded while corresponding to the direction of an exchange bias magnetic field to be impressed from the antiferromagnetic layer 15 to the magnetic layer 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic memory using a multilayer magnetoresistive film having a high magnetoresistance effect.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 6-295419 discloses a magnetic memory using a multilayer film exhibiting a giant magnetoresistance effect. This memory has features such as a short access time and a small cell area. Also, "Spin-Valve Memory Elements Using [[Co-Pt / Cu / Ni]" described in Jpn. J. Appl. Phys. Vol. 34, pp. L415-417 by Irie et al.
-Fe-Co] / Cu] Multilayers ", the use of two types of magnetic layers having different coercive forces makes it possible to obtain a memory capable of changing information.

[0003]

Some multilayer films exhibiting a giant magnetoresistance effect include Physical Review B, Vol. 43, No. 1 by Dienny et al.
"Giant Magnetoresistance in Soft Magnetic Multilayer Film" described on pages 1297-1300 (Giant Magnetoresistance in Soft
There is a multilayer film such as Ferromagnetic Multilayers in which two magnetic layers are separated by a non-magnetic layer, and one magnetic layer is applied with an exchange bias magnetic field from an antiferromagnetic layer.

The multilayer film has a large change in electric resistance with respect to a unit magnetic field, and is therefore being applied to a magnetoresistive head. However, even when a high magnetic field is applied, this type of multilayer film returns to its original state when the magnetic field is removed, and thus cannot be used for a magnetic memory as it is. An object of the present invention is to provide a magnetic memory using a multilayer film in which an exchange bias magnetic field from an antiferromagnetic layer is applied to one magnetic layer.

[0005]

Means for Solving the Problems The present inventors have studied the application to a magnetic memory of a multilayer film laminated in the order of an antiferromagnetic layer, a magnetic layer, a nonmagnetic layer, and a magnetic layer. The present inventors have found that information can be recorded in any memory cell by heating a memory cell composed of a multilayer film to near the blocking temperature of the antiferromagnetic layer and applying a magnetic field from the outside to complete the present invention. .

That is, a magnetic field is applied to the memory cell when the memory cell is heated to near the blocking temperature of the antiferromagnetic layer of the memory cell formed of the multilayer film and cooled. When a magnetic field is applied, the magnetic layer in contact with the antiferromagnetic layer is magnetized in the direction of the magnetic field. In the cooling process, the spin orientation of the antiferromagnetic layer is effected by the direction of the magnetization during the cooling of the magnetic layer. As a result, the direction of the exchange bias magnetic field applied from the antiferromagnetic layer to the magnetic layer is the direction of the magnetization of the magnetic layer during cooling, that is, the direction of the applied magnetic field during cooling. Therefore, by heating an arbitrary memory cell and applying a magnetic field during cooling, information corresponding to the direction of the applied magnetic field can be recorded in the arbitrary memory cell. Also, during this recording, unless other memory cells are heated and cooled,
Erroneous information is not written to other memory cells.

A magnetic memory according to the present invention comprises an antiferromagnetic layer,
A first magnetic layer, a non-magnetic layer, and a second magnetic layer, which are stacked in this order; and a recording value corresponding to a direction of an exchange bias magnetic field applied from the antiferromagnetic layer to the first magnetic layer. Is provided. The reproduction of the recorded value given to the multilayer film
The detection can be performed by providing a detecting means for detecting the electric resistivity of the multilayer film and a magnetic field applying means, and detecting the electric resistivity of the multilayer film while applying an external magnetic field whose direction changes by the magnetic field applying means. At this time, it is preferable that the magnetic field generating means generate a rotating magnetic field that rotates in the plane of the multilayer film, and the detecting means detect the electric resistivity of the multilayer film in synchronization with the rotation of the rotating magnetic field.

Further, the magnetic memory according to the present invention comprises a multilayer film in which an antiferromagnetic layer, a first magnetic layer, a non-magnetic layer, and a second magnetic layer are laminated in this order, and applying a magnetic field in a plurality of directions to the multilayer film. A magnetic field applying means for selectively applying a magnetic field, and a heating means for heating the multilayer film, wherein the heating means heats the multilayer film while applying a magnetic field in a predetermined direction to the multilayer film. A recording value is given by fixing the direction of magnetization of the first magnetic layer to the direction of the magnetic field applied by the magnetic field applying means by the action of an exchange bias magnetic field applied to the first magnetic layer from . The heating means desirably heats the multilayer film to a temperature equal to or higher than the blocking temperature of the antiferromagnetic layer, and the heating means may be a laser beam irradiation means.

Further, the magnetic memory according to the present invention comprises a plurality of memory cells each composed of a multilayer film laminated in the order of an antiferromagnetic layer, a first magnetic layer, a non-magnetic layer, and a second magnetic layer;
A magnetic field applying means for applying a magnetic field whose direction changes to the memory cell, and a detecting means for detecting an electric resistivity of the designated memory cell are provided. Preferably, the magnetic field applying means generates a rotating magnetic field that rotates in the plane of the multilayer film, and the detecting means detects an electric resistivity of the designated memory cell in synchronization with the rotation of the rotating magnetic field.

A magnetic memory according to the present invention comprises a plurality of memory cells each comprising a multilayer film laminated in the order of an antiferromagnetic layer, a first magnetic layer, a nonmagnetic layer, and a second magnetic layer;
A magnetic field applying unit for selectively applying magnetic fields in a plurality of directions to a memory cell and a heating unit for selectively heating a specified memory cell are provided. The heating means desirably heats the specified multilayer film to a temperature equal to or higher than the blocking temperature of the antiferromagnetic layer, and this heating means can be constituted by a laser beam irradiation means.

Referring to FIGS. 1 and 2, a recording (writing) method and an example of a reproducing (reading) method for the multilayer magnetic memory according to the present invention will be briefly described. The multilayer magnetic memory 10 according to the present invention comprises a magnetic layer 12, a non-magnetic layer 1
3, a magnetic layer 14, and an antiferromagnetic layer 15 are stacked in this order. The magnetic layers 12 and 14 can be layers made of the same magnetic material.

First, a recording method will be described with reference to FIG.
As shown in FIG. 1A, the multilayer film 10 is irradiated with a laser beam 20 and heated. The heating temperature is equal to or higher than the blocking temperature of the antiferromagnetic film 15. At this time, an external magnetic field H is applied to the multilayer film 10. Next, as shown in FIG.
The irradiation of the laser beam is stopped while the external magnetic field H is applied, and the multilayer film 10 is cooled. At this time, the magnetic layer 14 is magnetized in the direction of the external magnetic field H as indicated by the arrow in the figure. The spin orientation of the antiferromagnetic layer 15 is affected by the direction of magnetization during the cooling of the magnetic layer 14 during the cooling process.
As a result, as shown in FIG. 1C, the direction of the exchange bias magnetic field applied from the antiferromagnetic layer 15 to the magnetic layer 14 is
The direction of the magnetization of the magnetic layer 14 during cooling, that is, the direction of the applied magnetic field during cooling.

As shown in FIGS. 1D to 1F, when the direction of the external magnetic field H applied to the heated multilayer film 10 is reversed, the external magnetic field H is applied from the antiferromagnetic layer 15 to the magnetic layer 14. The direction of the exchange bias magnetic field is also reversed. In this way,
By heating the multilayer memory cell and applying a magnetic field during cooling, information corresponding to the direction of the applied magnetic field can be recorded in any memory cell.

Next, a method of reproducing (reading) the information recorded in the multilayer magnetic memory in this manner will be described with reference to FIG. FIG. 2 is a view for explaining a state when an external magnetic field rotating in the film plane of the multilayer film is applied to the multilayer magnetic memory, and FIG. 2 (a) shows the magnetic layer 1 in contact with the antiferromagnetic layer.
4 shows the change in the magnetization direction of the other magnetic layer 12, and FIG. 2B shows the change in the magnetic resistivity of the multilayer film.

Now, it is assumed that the magnetization of the magnetic film 14 is directed rightward in FIG. 2 by the exchange bias magnetic field applied from the antiferromagnetic layer 15 in contact with it. When a rotating magnetic field that rotates clockwise is applied to the multilayer film in this state, the direction of magnetization of the free magnetic film 12 is oriented in the same direction as the direction of the rotating magnetic field, as indicated by the arrow in FIG. Rotate together. On the other hand, the direction of magnetization of the magnetic film 14 is affected by the exchange bias magnetic field applied from the antiferromagnetic layer 15, and
Do not move while fixed to the right. Thus, the angle of the magnetization of the two layers of the magnetic layers 12 and 14, the time t ₁ in the orthogonal direction, the time t in the _second parallel direction, the time t ₃ in orthogonal directions, the time t ₄ in antiparallel, at time t ₅ It changes cyclically with the orthogonal direction.

The magnetic resistivity of the multilayer magnetic memory 10 is 2
When the magnetization directions of the two magnetic layers are parallel to each other, the value is minimum, and when the magnetization directions of the two magnetic layers are antiparallel to each other, the value is maximum. Therefore, the magnetoresistance ratio of the multilayer film magnetic memory 10, the applied magnetic field is changed as shown in FIG. 2 (b) when rotated, the direction of the rotating magnetic field at time t ₂ when the magnetoresistance ratio takes a minimum value or, Time t _{4 at} which the magnetic resistivity takes a maximum value
From the direction of the rotating magnetic field at the time, the direction of the magnetization of the magnetic film 14;
That is, information recorded in the multilayer magnetic memory 10 can be reproduced. As is apparent from this, the magnetic memory according to the present invention can perform multi-level recording corresponding to the direction of the exchange bias magnetic field applied from the antiferromagnetic layer in the memory cell to the magnetic layer adjacent thereto.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a schematic plan view showing an example of the recording / reproducing system of the magnetic memory according to the present invention. FIG. 3 shows a magnetic memory including nine memory cells 10a to 10i. One memory cell is, for example, 1 μm
It has a size of about × 1 μm. Each memory cell 10a-1
Oi is connected to the current application / voltage detection system 17 by conductors 16a to 16x. In addition, the memory cells 10a to
Coils 21 and 22 for applying a magnetic field to 10i are provided.

FIG. 4 is a schematic sectional view taken along the line AA of FIG. 3, and shows a schematic structure of an example of the magnetic memory according to the present invention. Each of the memory cells 10a, 10b, and 10c of the magnetic memory includes a magnetic layer 12 and a non-magnetic layer 1 stacked on a substrate 11, respectively.
3, a multilayer film composed of a magnetic layer 14 and an antiferromagnetic layer 15. Here, a Ni-20 at% Fe alloy having a thickness of 5 nm is used as the magnetic layer 12 and the magnetic layer 14.
As a nonmagnetic layer, Cu having a thickness of 2.5 nm was deposited on the antiferromagnetic layer 1.
As Mn-22 at% Ir alloy having a thickness of 10 nm was used as 5. The antiferromagnetic layer 15 is preferably formed on the magnetic layer 14, but the stacking order is reversed to form the antiferromagnetic layer 15 on the substrate 11, and the magnetic layer 14 is formed thereon. No problem. A memory cell 10a composed of each multilayer film,
10b and 10c are connected to a current application / voltage detection system 17 by conductors 16a to 16d made of Au.

The current application / voltage detection system 17 includes a conductor 16a
The current of the memory cell is reproduced while an external magnetic field is applied by two pairs of magnetic field applying coils 21 and 22 for applying a current to the memory cell and applying a magnetic field to the memory cell through .about.16x. In this case, it is preferable to apply a rotating magnetic field during reproduction. By controlling the two pairs of magnetic field applying coils 21 and 22, a rotating magnetic field can be applied to each memory cell. The applied magnetic field needs to be lower than the exchange bias magnetic field applied to the magnetic layer 14. When the direction of magnetization of the magnetic layer 14 in the memory cell matches the direction of the rotating magnetic field, that is, the direction of magnetization of the magnetic layer 12, the electrical resistivity of the memory cell becomes minimum. By detecting such a change in the electrical resistance of the memory cell by the current application / voltage detection system 17, information written in the memory cell can be reproduced.

A specific memory cell, for example, memory cell 10
When recording (writing) is performed on the memory cell 10c, the memory cell 10c composed of a multilayer film is irradiated with a laser beam 20 by a mechanism 18 for generating a laser beam and an optical system 19, as schematically shown in FIG. Heat 10c. If the heating is performed up to the vicinity of the blocking temperature of the antiferromagnetic layer 15 constituting the memory cell 10c or more, recording can be performed efficiently. When the irradiation of the laser beam 20 is stopped after heating the memory cell 10c, the memory cell 10c is cooled. In the cooling process, when a magnetic field is applied by the magnetic field applying coils 21 and 22 for applying a magnetic field to the memory cell 10c, the magnetization direction during cooling of the magnetic layer 14 is affected, and the antiferromagnetic layer 15
Is performed. As a result, the direction of the exchange bias magnetic field applied from the antiferromagnetic layer 15 to the magnetic layer 14 is
The direction of the magnetization of the magnetic layer 14 during cooling, that is, the direction of the applied magnetic field during cooling.

As described above, an arbitrary memory cell is heated,
By applying a magnetic field during cooling, information corresponding to the direction of the applied magnetic field can be recorded in any memory cell. The direction of the applied magnetic field can be set arbitrarily within the film surface of the multilayer film. At the time of reproduction, which will be described later, if the resolution for detecting the direction of magnetization of the magnetic layer 14 is high, the larger the value, the larger the value of one memory cell. Can be recorded. For example, as shown in FIG. 5, four-level recording is possible by directing the magnetization of the magnetic layer 14 of the multilayer film forming the memory cell to one of the four directions A, B, C, and D of the memory cell 10. It is. In addition to quaternary recording, for example, an angular resolution of 30
If it is a degree, record 12 values in one memory cell 1
Binary recording becomes possible. Further, by providing a mechanism for irradiating the above-mentioned arbitrary multilayer film with the laser beam, random access recording becomes possible.

Next, an example of a method for reproducing information recorded in a memory cell will be described with reference to FIG. 6 together with FIG. For example, to reproduce the information of the memory cell 10a, the conductor 16a that contacts the memory cell 10a at the contact 23a
The memory cell 10 is connected to the conductor 16m in contact with the contact 23b.
a is supplied with a constant current 24a. At this time, while applying an external magnetic field by the coils 21 and 22 for applying a magnetic field to the memory cell, the voltage between the contacts 23c and 23d is measured to reproduce the information of the memory cell 10a. To reproduce the information in the memory cell 10b, a constant current 24b is passed through the memory cell 10b by the conductors 16b and 16n, and the contacts 23g and 23h
Measure the voltage between them.

In order to reproduce information from the memory cell 10e, a current flows through the memory cell 10e through the conductors 16e, 16f, 16q, and 16n. In this case, the current flows through the conductors 16p and 16b to the memory cell 10a. The current also shunts. However, since the information of the memory cell 10a has been read in advance, the current flowing in the memory cell 10e is clear, and the electric resistance of the memory cell 10e can be measured. In this way, information of an arbitrary memory cell can be reproduced.

FIG. 7 is a schematic plan view showing another example of the recording / reproducing system of the magnetic memory according to the present invention, and FIG. 8 is a schematic diagram showing an AA section thereof. In the magnetic memory, electrodes 51, 52 and 53 in the X direction (see FIG. 7) are formed on a substrate 11 such as Si, and memory cells 10a to 10c are
2, memory cells 10d to 10f are formed on the electrode 53, and memory cells 10g to 10i are formed on the electrode 53 such that the lower magnetic film of each memory cell is in contact with the electrode. The space between adjacent memory cells is filled with an insulator 25 such as SiO ₂ . On the memory cells 10a to 10i, the electrodes 56, 57,
58 is formed. The electrode 56 is connected to the memory cells 10a, 10
The electrode 57 contacts the antiferromagnetic layers of the memory cells 10b, 10e, and 10h, and the electrode 58 contacts the antiferromagnetic layers of the memory cells 10b, 10e, and 10h.
Contacts the antiferromagnetic layers of the memory cells 10c, 10f, and 10i.

Each memory cell 10a to 10i of the magnetic memory
Is similar to the structure described with reference to FIGS. 3 and 4, and includes a magnetic layer 12, a nonmagnetic layer 13, a magnetic layer 14, and an antiferromagnetic layer 15 laminated on a substrate 11, respectively. Here, the magnetic layers 12 and 14 have a thickness of 5 nm.
Ni-20 at% Fe alloy, Cu having a thickness of 2.5 nm as a nonmagnetic layer, and a 10 n
m of Mn-22 at% Ir alloy was used.

Each of the electrodes 51 to 53 and 56 to 58 is connected to a current application / voltage measurement system 17, and the current application / voltage measurement system 17 is selectively connected to the multilayer film of the specified memory cells 10a to 10i. A current (constant current) is passed, and the voltage of the multilayer film through which the current flows can be measured. Memory cell 1
The coils 21 and 21 for generating a magnetic field in the X direction and the coils 22 and 21 for generating a magnetic field in the Y direction
22, two coil pairs are arranged.
By controlling the current flowing through 21 and the current flowing through coils 22, 22, a rotating magnetic field that rotates in the XY plane can be applied to each of memory cells 10a to 10i. The size of one of the memory cells 10a to 10i can be about 1 μm × 1 μm.

As described with reference to FIG. 4, the recording in the designated memory cell is performed by controlling the current flowing through the coils 21 and 22 while heating the designated memory cell by the laser beam. Can be controlled by controlling the direction. At this time, if two pairs of magnetic field applying mechanisms, that is, the coils 21 and 22, are used, multi-value recording can be performed on the memory cell as described above.

When multi-value recording is performed, it is preferable to apply a rotating magnetic field to the memory cell during reproduction. By controlling the two pairs of magnetic field applying coils 21 and 22, a rotating magnetic field can be applied to each memory cell. When the direction of the magnetization of the magnetic layer 12 in the memory cell matches the direction of the rotating magnetic field, the electrical resistivity of the memory cell becomes minimal, and the direction of the magnetization of the magnetic layer 12 and the direction of the rotating magnetic field are antiparallel. , The electrical resistivity of the memory cell becomes maximum. By detecting such a change in the electric resistivity of the memory cell by the current application / voltage detection system 17, information written in the memory cell can be reproduced.

FIG. 9 is a schematic block diagram of a reproduction signal processing system of a magnetic memory according to the present invention. This reproduction signal processing system includes a phase signal generation system 61, a phase comparison system 63, and an information conversion system 64. The phase generation system 61 outputs a continuously changing phase signal or, for example, 0 °, 90 °, 180 °, 27 °.
A phase signal that changes intermittently at 0 ° and 0 ° is generated, and this phase signal is supplied to a coil current control system 62 and a phase comparison system 63. The coil current control system 62 controls the exciting current flowing through the magnetic field applying coils 21 and 22 so as to generate a magnetic field in a direction corresponding to the input phase signal. Here, the direction of A in FIG.
Direction 90 °, direction C 180 °, direction D 27
An angle is defined clockwise, such as 0 °. Therefore, for example, the coil current control system 62 that has received the phase signal of 0 ° from the phase generation system 61
Magnetic field applying coils 21 and
2 is controlled.

The current application / voltage detection system 17 detects the voltage of the specified memory cell as described above. The voltage of the memory cell detected by the current application / voltage detection system 17 is compared with the phase signal supplied from the phase signal generation system 61 by the phase comparison system 63. Information is output from the phase comparison system 63 to the information conversion system 64 at the next stage. In the information conversion system 64,
Based on the input phase information, the value recorded in the memory cell is reproduced and output.

The operation of the reproduction signal processing system will be described with reference to FIG. FIG. 10 shows two pairs of magnetic field applying coils 2
FIG. 9 is a diagram showing an example of a relationship between a phase of an external magnetic field generated at a position of a memory cell by a voltage detection system and a voltage change of the memory cell detected by a voltage detection system for each recorded value of the memory cell. FIG. 10A is a diagram showing the phase of the external magnetic field applied to the memory cell by the magnetic field applying coils 21 and 22 by the intensity of the magnetic field with the direction A in FIG. Now, the recorded value “0” is in the state of A in FIG. 5 where the magnetization direction of the magnetic layer 14 of the memory cell is 0 °, the recorded value “1” is in the state of B where it is 90 °, and 180 °. It is assumed that the recording value “2” is assigned to the state C and the recording value “3” is assigned to the state D which is 270 °.

FIG. 10B shows a memory cell detected by the current application / voltage detection system 17 when the recorded value of the memory cell is “0”, that is, when the direction of magnetization of the magnetic layer 14 is 0 °. 3 shows a voltage waveform of the first embodiment. At this time, the voltage waveform detected by the current application / voltage detection system 17 is input when the direction of magnetization of the magnetic layer 14 matches the direction of the external magnetic field, that is, from the phase signal generation system 61 to the phase comparison system 63. It takes a minimum value when the phase signal is 0 °, and takes a maximum value when the phase signal is 180 ° where the direction of the magnetization of the magnetic layer 14 and the direction of the external magnetic field are antiparallel. The phase comparison system 63 transmits to the information conversion system 64 that the output of the current application / voltage detection system 17 takes a local minimum value when the phase is 0 ° or a local maximum value when the phase is 180 °. Outputs "0" based on the conversion table.

FIG. 10C shows the case where the recorded value of the memory cell is “1”, that is, the magnetization direction of the magnetic layer 14 is 90 °.
The voltage waveform of the memory cell detected by the current application / voltage detection system 17 when the direction is the direction is shown. At this time, the voltage waveform detected by the current application / voltage detection system 17 is input when the direction of magnetization of the magnetic layer 14 matches the direction of the external magnetic field, that is, from the phase signal generation system 61 to the phase comparison system 63. It takes a minimum value when the phase signal is 90 °, and takes a maximum value when the phase signal is 270 ° where the magnetization direction of the magnetic layer 14 and the direction of the external magnetic field are antiparallel. The phase comparison system 63 is such that the output of the current application / voltage detection system 17 has a minimum value at a phase of 90 °,
Alternatively, it is transmitted to the information conversion system 64 that the maximum value is obtained at the phase of 270 °, and the information conversion system 64 outputs “1” by referring to the conversion table.

FIG. 10D shows that the recorded value of the memory cell is “2”, that is, the magnetization direction of the magnetic layer 14 is 180.
FIG. 10E shows the voltage waveform of the memory cell detected by the current application / voltage detection system 17 when the direction is the ° direction. FIG. 10E shows the case where the recorded value of the memory cell is “3”, that is, the magnetization of the magnetic layer 14. The voltage waveform of the memory cell detected by the current application / voltage detection system 17 when the direction is the 270 ° direction is shown. Similarly, the phase comparison system 63 detects the phase at which the voltage waveform of the memory cell detected by the current application / voltage detection system 17 has a minimum value or a maximum value, and outputs the phase to the information conversion system 64. The information conversion system 64 compares the phase information supplied from the phase comparison system 63 with the conversion table, and
In this case, "2" is output, and in the case of FIG. 10E, "3" is output. In this manner, the magnetic memory according to the present invention can perform multi-level recording corresponding to the direction of the exchange bias magnetic field applied from the antiferromagnetic layer 15 in the memory cell to the magnetic layer 14 in contact with it.

Here, a Ni-20 at% Fe alloy having a thickness of 5 nm is used as the magnetic layer 12 and the magnetic layer 14.
As a nonmagnetic layer, Cu having a thickness of 2.5 nm was deposited on the antiferromagnetic layer 1.
Although the case where a Mn-22 at% Ir alloy having a thickness of 10 nm is used as 5 has been described, the same effect can be obtained with other magnetic layer materials. An insulating material can be used for the nonmagnetic layer. When an insulating material is used for the nonmagnetic layer, it is necessary to apply a voltage between the two magnetic layers from electrodes provided above and below the multilayer film, and electrons need to tunnel through the insulating layer.

[0036]

According to the present invention, an antiferromagnetic layer, a magnetic layer,
A memory cell is formed by a multilayer film in which a non-magnetic layer and a magnetic layer are stacked in this order, and information corresponding to the direction of an applied magnetic field can be recorded and reproduced in an arbitrary memory cell. Further, at the time of recording, unless other memory cells are heated or cooled, erroneous information is not written in other memory cells.

[Brief description of the drawings]

FIG. 1 is a view for explaining a recording (writing) method to a multilayer magnetic memory according to the present invention.

FIG. 2 is a view for explaining a reproducing (reading) method of the multilayer magnetic memory according to the present invention.

FIG. 3 is a schematic plan view showing an example of a recording / reproducing system of a magnetic memory according to the present invention.

FIG. 4 is a schematic sectional view taken along the line AA in FIG. 3;

FIG. 5 is a plan view showing a memory cell and a recording direction.

FIG. 6 is a schematic diagram for explaining an example of a method of reproducing information of a specified memory cell.

FIG. 7 is a schematic plan view showing another example of the recording / reproducing system of the magnetic memory according to the present invention.

FIG. 8 is a schematic sectional view taken along the line AA of FIG. 7;

FIG. 9 is a schematic block diagram of a reproduction signal processing system of a magnetic memory according to the present invention.

FIG. 10 is a diagram showing an example of a relationship between a phase of an external magnetic field generated at a position of a memory cell and a voltage change of the memory cell detected by a voltage detection system for each recorded value of the memory cell.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Multilayer magnetic memory, 10a-10i ... Memory cell, 11 ... Substrate, 12, 14 ... Magnetic layer, 13 ... Nonmagnetic layer, 15 ... Antiferromagnetic layer, 16a-16x ... Conductor, 17 ...
Current application / voltage detection system, 18: mechanism for generating laser light, 19: optical system, 20: laser light, 21, 22, ... magnetic field application coil, 23a to 23h: contacts, 24a, 24b ...
Constant current, 25: insulator, 51 to 53: electrode, 56 to 58
... electrodes, 61 ... phase signal generation system, 62 ... coil current control system, 63 ... phase comparison system, 64 ... information conversion system

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[Procedure amendment]

[Submission date] May 14, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Claims (11)

[Claims] An antiferromagnetic layer, a first magnetic layer, a nonmagnetic layer,
A magnetic layer provided in the order of a second magnetic layer, wherein a recording value is given in accordance with a direction of an exchange bias magnetic field applied from the antiferromagnetic layer to the first magnetic layer. memory. 2. The magnetic memory according to claim 1, further comprising: a detection unit for detecting an electric resistivity of the multilayer film; and a magnetic field application unit, wherein the magnetic field application unit applies an external magnetic field whose direction changes. A magnetic memory for reproducing a recorded value by detecting an electric resistivity of the multilayer film. 3. The magnetic memory according to claim 2, wherein said magnetic field generating means generates a rotating magnetic field which rotates in the plane of said multilayer film, and said detecting means generates said rotating magnetic field in synchronization with rotation of said rotating magnetic field. A magnetic memory characterized by detecting an electric resistivity of the magnetic memory. 4. An antiferromagnetic layer, a first magnetic layer, a nonmagnetic layer,
A multilayer film laminated in the order of the second magnetic layer; and a magnetic field applying unit for selectively applying magnetic fields in a plurality of directions to the multilayer film;
Heating means for heating the multilayer film; heating the multilayer film by the heating means while applying a magnetic field in a predetermined direction to the multilayer film by the magnetic field applying means; Wherein the recording value is given by fixing the direction of magnetization of the first magnetic layer to the direction of the magnetic field applied by the magnetic field applying means by the action of an exchange bias magnetic field applied to the magnetic layer. memory. 5. The recording / reproducing apparatus according to claim 4, wherein said heating means heats said multilayer film to a temperature equal to or higher than a blocking temperature of said antiferromagnetic layer. 6. The magnetic memory according to claim 4, wherein said heating means is a laser beam irradiation means. 7. An antiferromagnetic layer, a first magnetic layer, a nonmagnetic layer,
A plurality of memory cells each composed of a multilayer film laminated in the order of the second magnetic layer; magnetic field applying means for applying a changing magnetic field to the memory cells; and detecting an electrical resistivity of the designated memory cell A magnetic memory, comprising: a detection unit. 8. The magnetic memory according to claim 7, wherein said magnetic field applying means generates a rotating magnetic field which rotates in the plane of said multilayer film, and said detecting means is designated in synchronization with the rotation of said rotating magnetic field. A magnetic memory characterized by detecting an electric resistivity of a memory cell. 9. An antiferromagnetic layer, a first magnetic layer, a nonmagnetic layer,
A plurality of memory cells each composed of a multilayer film laminated in the order of the second magnetic layer; a magnetic field applying means for selectively applying a magnetic field in a plurality of directions to the memory cells; A magnetic memory, comprising: heating means for heating. 10. The magnetic memory according to claim 9, wherein
The recording / reproducing apparatus according to claim 1, wherein the heating means heats the specified multilayer film to a temperature higher than a blocking temperature of the antiferromagnetic layer. 11. The magnetic memory according to claim 9, wherein said heating means is a laser beam irradiation means.