JP3350311B2 - Magnetic thin film memory element and magnetic thin film memory - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic thin film memory element and a magnetic thin film memory for recording information according to the magnetization direction of a magnetic layer.

[0002]

2. Description of the Related Art In recent years,
Devices such as thin-film magnetic heads and magnetic thin-film memories utilizing the magnetoresistive effect have been developed. Conventionally, as a magnetoresistive effect material, NiFe (permalloy) or the like to which the anisotropic magnetoresistive (AMR) effect is applied has been representative. AMR is a phenomenon in which the electric resistance changes depending on the relative angle between the magnetization of the magnetic material and the sense current, and the resistance change rate is at most about 3% in Permalloy.

On the other hand, an artificial lattice film in which magnetic layers and non-magnetic layers are alternately laminated is known to show a large magnetoresistance change called a giant magnetoresistance (GMR) effect, and has been actively used in both basic and applied aspects. Has been studied. GMR effect is AM
Unlike the R effect, the rate of change in resistance depends not on the relative angle between the magnetization and the current but on the relative angle between the magnetizations of the two magnetic layers stacked via the nonmagnetic layer.

[0004] In particular, GMR materials having a structure called a spin valve have attracted attention in application because they have a small operating magnetic field and show a larger rate of resistance change than AMR materials. The spin valve basically has a three-layer structure including two magnetic layers stacked with a non-magnetic layer interposed therebetween. Here, the magnetization direction of one magnetic layer is fixed (pinned layer), and the magnetization direction of the other magnetic layer can move freely by a relatively weak external magnetic field. Also, the axes of easy magnetization of both magnetic layers are parallel, and the magnetization directions of both magnetic layers can be in the same direction or opposite directions due to an external magnetic field.
The resistance value changes.

[0005] For example, Phys. Rev .. B, 43,
p1297, (1991) shows an example of an element in which a magnetic layer NiFe / nonmagnetic layer Cu / magnetic layer NiFe / antiferromagnetic layer FeMn is laminated. Here, the antiferromagnetic layer F
The magnetization direction of the NiFe magnetic layer (pinned layer) laminated in contact with eMn is fixed by the exchange coupling force with FeMn. On the other hand, the other NiFe magnetic layer (free layer) can freely change its magnetization direction by an external magnetic field, and as a result, exhibits the GMR effect.

[0006] Jpn. J. Appl. Phys. ,
33, L1668, (1994) show an example in which CoPt (hard layer) having a large coercive force and NiFeCo (soft layer) having a small coercive force are laminated via a nonmagnetic layer Cu. Here, the magnetization direction of the soft layer can be freely moved by a relatively weak external magnetic field, and as a result, the GMR effect is obtained. G of the type using such a coercive force difference
MR is called an induced ferri type, as distinguished from the spin valve using the antiferromagnetic layer described above.

Some proposals have been made for a magnetic thin film memory utilizing the magnetoresistance effect.

[0008] For example, IEEE Trans. Ma
g. , 26, p2828, (1990) include FIG.
An AMR magnetic memory having a configuration as shown in FIG. This AMR magnetic memory uses a sandwich film in which two types of magnetic layers 71 and 73 are laminated via a non-magnetic layer 72, and a digit current 75 is passed through the sandwich film during recording and reproduction. Are arranged so that a word current 77 flows in a direction perpendicular to this. Recording and reproduction are performed by a magnetic field 76 and a magnetic field 78 generated by the digit current 75 and the word current 77.

First, at the time of recording, a word current 77 and a digit current 75 are passed, and the magnetization directions of the two magnetic layers in a steady state after the current is cut off change depending on the direction of the digit current. The information “0” and “1” correspond to the magnetization directions of the two magnetic layers.

On the other hand, at the time of reproduction, a weaker current is applied to the word line 74 than during recording, and at the same time, a detection current is applied to the digit line 73. Since the magnetization directions of the two magnetic layers are different depending on the information (“0” or “1”) recorded at this time, a difference occurs in the resistance value due to the AMR effect. By detecting the difference in the resistance value, the recording is performed. It is possible to determine whether the information being performed is “0” or “1”. In this method, information can be reproduced in a non-destructive manner (the recorded state is maintained even after the reproduction), and the consumption current is small. However, since the resistance change rate is small, the detection signal is small.
There is a disadvantage that the S / N (signal / noise) ratio is low.

On the other hand, as a magnetic thin film memory utilizing GMR, US Pat. No. 5,343,422 exemplifies a memory having a spin valve type structure of an antiferromagnetic layer / magnetic layer / nonmagnetic layer / magnetic layer.

[0012]

Next, a method of recording information in a magnetic thin film memory using the spin valve type MR magnetic layer will be described.

FIGS. 12A and 12B show a case where information is recorded on a spin-valve type magnetic thin film memory element (a case where information is recorded on a free layer), where 21 is a write line, and 31 is a pin layer. The corresponding first magnetic layer, 32 is a non-magnetic layer, 3
Reference numeral 3 denotes a second magnetic layer corresponding to the free layer. Here, the axes of easy magnetization of the first magnetic layer 31 and the second magnetic layer 33 are parallel, and
These easy axes are set in a direction perpendicular to the write line 21. Reference numerals 22 and 23 denote magnetic fields generated by a write current flowing through the write line 21, and the direction of the magnetic field is determined by the direction of the write current flowing through the write line 21. By the magnetic field 22 or 23 generated by the write current, the magnetization direction of the second magnetic layer 33 corresponding to the free layer is set to the direction of the applied magnetic field,
Information is recorded by associating binary “0” and “1” with the direction of the magnetic field . In FIG. 12A, the magnetic field (clockwise magnetic field) 22 generated by the write current flowing through the write line 21 causes the second magnetic layer 33 to reverse the magnetization direction of the first magnetic layer 31. (Left direction on the paper). On the other hand, in (b), the magnetic field (counterclockwise magnetic field on the paper) 23 generated by the write current flowing through the write line 21 causes the second magnetic layer 33 to synchronize with the magnetization direction of the first magnetic layer 31. They are magnetized in the same direction (rightward on the paper). When a magnetic field generated by a write current flowing through the write line 21 (hereinafter, referred to as a recording magnetic field) is larger than a magnetic field that causes the magnetization reversal of the first magnetic layer 31 corresponding to the pinned layer, when a recording magnetic field is applied, The one magnetic layer 31 is also magnetized in the direction of the recording magnetic field, but returns to the state before the application of the recording magnetic field when the recording magnetic field is removed.

Next, the case of reproducing the information recorded as described above will be described with reference to FIGS. 12 (c) and 12 (d). FIG. 12 (c) shows a case where information recorded by the magnetic field 22 shown in FIG . 12 (a) is reproduced .
(D) shows a case where information recorded by the magnetic field 23 shown in (b) is reproduced.

When reproducing information recorded by the magnetic field 22 or the magnetic field 23, a pulse current (hereinafter referred to as a reproduction current) is supplied to the write line 21 in a certain direction while a read current is supplied to the read line 25. . Here, the magnetic field 2 generated by the reproduction current flowing through the write line 21
4 is larger than the coercive force of the second magnetic layer 33, but does not reverse the magnetization direction of the first magnetic layer 31.

In the case of FIG . 12C , the magnetic field 22 when information is recorded and the magnetic field 24 generated by the reproducing current are in opposite directions, so that when the reproducing current flows, the magnetization of the second magnetic layer 33 is reduced. The direction is reversed, and the magnetic thin film memory element M
The resistance value of the R magnetic layer decreases. As a result, a voltage change (voltage rise) occurs on the output side of the read line 25 through which the read current flows. On the other hand, in the case of (d), the magnetic field 23 when information is recorded and the magnetic field 2 generated by the reproduction current
4 are in the same direction, the second
The magnetization direction of the magnetic layer 33 does not reverse, and the resistance value of the MR magnetic layer, which is a magnetic thin film memory element, does not change. Accordingly, no voltage fluctuation occurs on the output side of the read line 25 through which the read current flows.

In other words, "0" and "1", which are information corresponding to the magnetization direction, can be determined based on whether or not a voltage fluctuation occurs when a reproduction current is passed.

However, in this method, the output of the reproduction signal is large because the GMR is used. However, when the magnetization reversal occurs in the second magnetic layer (free layer) when reproducing the information,
Since the recorded information is destroyed, there is a disadvantage that the information can be reproduced only once.

Also, Jpn. J. Appl. Phys. P
Art2, 34, L415 (1995) shows an example of a memory element using an induction ferri-type structure of a hard layer / non-magnetic layer / soft layer. In this inductive ferrimagnetic type, when information is recorded, the hard layer is magnetized in the direction of the magnetic field by the magnetic field generated by the current flowing through the write line, and "0" and "1" are made to correspond to the magnetization direction of the hard layer. To record information. At the time of reproduction, a pulse current of which polarity changes (flow direction changes) is applied to the write line while a constant current flows to the read line, and only the magnetization direction of the soft layer is changed by the magnetic field generated by the current. Change according to the change in the magnetic field (at this time, the magnetization direction of the hard layer does not change). At this time, the resistance value of the element changes from low resistance to high resistance or from high resistance to low resistance depending on the magnetization direction of the hard layer. The magnetization direction of the magnetic layer is determined.

However, in this method, reproduction can be performed without destroying information. However, power consumption at the time of writing is large, and after reproduction, the magnetization directions of the first magnetic layer and the second magnetic layer are reversed. When the reading direction is reached, the state, that is, the high resistance state is maintained, so that the power consumption of the portion irrelevant to the information reproduction (the power consumption in the memory element in which the high resistance is maintained when the read current flows) is maintained. ) Also increased, making it difficult to reduce power consumption.

In order to solve the above problems, Japanese Patent Laid-Open Publication No.
Japanese Patent Application Publication No. 02184 discloses a magnetic thin film memory which consumes relatively low power and does not destroy information during reproduction. Here, as the MR magnetic layer, a multilayer film in which two or more types of magnetic layers having different coercive forces are alternately stacked via a nonmagnetic layer is used, and these magnetic layers are exchange-coupled to each other. In this magnetic thin film memory, both the magnetic layer having a large coercive force and the magnetic layer having a small coercive force direct the magnetization direction to the direction of the recording magnetic field at the time of recording, but only the magnetic layer having the small coercive force changes the magnetization direction to the reproducing magnetic field at the time of reproduction. After reproduction, the magnetization of the magnetic layer having a weak coercive force returns to the same direction as the magnetization direction of the magnetic layer having a large coercive force due to the exchange coupling force from the magnetic layer having a large coercive force. I have. However, this magnetic thin film memory has a complicated structure of the MR magnetic layer and is not suitable for industrialization, and it is difficult to provide a low-cost magnetic thin film memory.

Accordingly, an object of the present invention is to provide a magnetic thin film memory element and a magnetic thin film memory which have a simple configuration, consume less power, and can reproduce information in a non-destructive manner.

[0024]

According to a first aspect of the present invention, there is provided a magnetic thin film memory device comprising a first magnetic layer, a non-magnetic layer, a second magnetic layer, and a third magnetic layer laminated in this order or vice versa. In the magnetic thin film memory device, the coercive force of the first magnetic layer and the third magnetic layer is larger than the coercive force of the second magnetic layer, and the second magnetic layer and the third magnetic layer come into direct contact and exchange-coupled. It is characterized by having.

According to a second aspect of the present invention, there is provided a magnetic thin film memory element for recording information as a magnetization direction, a read line for detecting a change in resistance of the magnetic thin film memory element, and a magnetic field applied to the magnetic thin film memory element. In a magnetic thin film memory having a write line for applying a magnetic field, the magnetic thin film memory element includes a first magnetic layer, a nonmagnetic layer, a second magnetic layer, and a third magnetic layer in this order or vice versa. in a laminated the thin film, the coercive force of the first magnetic layer and the third magnetic layer is greater than the coercive force of the second magnetic layer, the second magnetic layer and the third magnetic layer linear
It is characterized by being in contact and exchange-coupled.

According to a third aspect of the present invention, there is provided the magnetic thin film memory according to the second aspect, wherein a magnetic field applied to the magnetic thin film memory element at the time of writing is larger than the coercive force of the third magnetic layer. A magnetic field smaller than the coercive force of the magnetic layer, and the magnetic field applied to the magnetic thin film memory element at the time of reading is larger than the coercive force of the second magnetic layer in a stacked state;
The magnetic field is smaller than the coercive force of the third magnetic layer.

According to a fourth aspect of the present invention, there is provided the magnetic thin film memory according to the second aspect, wherein a magnetic field applied to the magnetic thin film memory element at the time of writing is controlled by the first magnetic layer and the third magnetic layer.
The coercive force of the magnetic layer is larger than the coercive force of the first magnetic layer and the coercive force of the first magnetic layer and the third magnetic layer when the magnetic field applied to the magnetic thin film memory element at the time of reading is larger than the coercive force of the second magnetic layer. It is a magnetic field.

According to a fifth aspect of the present invention, there is provided a magnetic thin film memory element comprising an antiferromagnetic layer, a first magnetic layer, a nonmagnetic layer, a second magnetic layer, and a third magnetic layer stacked in this order or in the reverse order. In the thin film memory device, the coercive force of the third magnetic layer is larger than the coercive force of the second magnetic layer, and the second magnetic layer and the third magnetic layer are exchange-coupled.

According to a sixth aspect of the present invention, there is provided a magnetic thin film memory element for recording information as a magnetization direction, a read line for detecting a change in resistance of the magnetic thin film memory element, and a magnetic field applied to the magnetic thin film memory element. In a magnetic thin film memory having a write line for applying a magnetic field, the magnetic thin film memory element includes an antiferromagnetic layer, a first magnetic layer, a nonmagnetic layer, a second magnetic layer, and a third magnetic layer in this order or and characterized in that it consists of a thin film formed by laminating in the order of the reverse, the coercive force of the third magnetic layer is greater than the coercive force of the second magnetic layer, the second magnetic layer and the third magnetic layer are exchange-coupled Is what you do.

According to a seventh aspect of the present invention, there is provided the magnetic thin film memory according to the sixth aspect, wherein a magnetic field applied to the magnetic thin film memory element at the time of writing is larger than the coercive force of the third magnetic layer. Wherein the magnetic field applied to the magnetic thin-film memory element is a magnetic field larger than the coercive force of the second magnetic layer in the stacked state and smaller than the coercive force of the third magnetic layer. .

In the above, at the time of writing (at the time of recording),
The magnetic field applied to the thin-film magnetic memory element is a magnetic field (recording magnetic field) generated by a write current flowing through a write line.
Therefore, the magnetic field applied to the thin-film magnetic memory element at the time of reading (at the time of reproduction) is a magnetic field (reproduction magnetic field) generated by a reproduction current flowing through the write line.

[0032]

According to the magnetic thin film memory of the present invention, the second layer corresponding to the free layer or the soft layer constituting the memory element is provided.
Since the magnetic layer and the third magnetic layer are composed of two types of magnetic layers exchange-coupled to each other having different coercive forces, when information is recorded on the free layer or the soft layer (the recording magnetic field is maintained by the first magnetic layer). (When the magnetic force is smaller), during reproduction, only the second magnetic layer is magnetized in the direction of the reproducing magnetic field, and after reproduction, the reproducing magnetic field is removed to change the magnetization direction of the second magnetic layer.
The magnetization direction before reproduction can be returned by the exchange magnetic field from the third magnetic layer. Therefore, the recorded information can be reproduced nondestructively.

On the other hand, when the first magnetic layer corresponding to the hard layer and the third magnetic layer corresponding to the soft layer are magnetized in the same magnetization direction and information is recorded as the magnetization direction (the recording magnetic field is the first magnetic layer). (When the coercive force is greater than the coercive force of the magnetic layer), during reproduction, only the second magnetic layer is magnetized in the direction of the reproducing magnetic field, and after reproduction, the reproducing magnetic field is removed, so that the magnetization of the second magnetic layer which has undergone magnetization reversal during reproduction is reduced. The magnetization direction can be returned to the same magnetization direction as the first and third magnetic layers by the exchange magnetic field from the third magnetic layer. Therefore, the resistance value of the magnetic thin film memory element in a state where no reproducing magnetic field is applied can always be in a low resistance state.

[0034]

FIG. 1A is a cross-sectional view of a magnetic thin film memory according to the present invention, showing one cell which is the minimum unit of the memory for explaining the basic operation of the magnetic thin film memory. . In FIG. 1, a magnetic thin-film memory element composed of an MR magnetic layer 1, a read line 2, and a write line 4 are provided on a substrate 5 via an insulating layer 3 to constitute a magnetic thin-film memory. Here, the substrate 5 is preferably an insulator such as glass or a surface-oxidized Si wafer.

In the present invention, the MR magnetic layer constituting the magnetic thin film memory element may have any structure of a spin valve type or an induction ferri type.

Next, the MR constituting the magnetic thin film memory element will be described.
The magnetic layer will be described with reference to the sectional views of the MR magnetic layer shown in FIGS.

(In the case of a spin valve type structure) FIG. 1 (b)
Shows an MR magnetic layer having a spin-valve structure, and a third magnetic layer 15, a second magnetic layer 14,
The nonmagnetic layer 13, the first magnetic layer 12, and the antiferromagnetic layer 11 are stacked in this order. Here, the second magnetic layer 14 and the third
The magnetic layer 15 corresponds to a free layer in a pair, and the first magnetic layer 12 corresponds to a pinned layer.

The order of laminating each layer is opposite to that of FIG. 1B, and the antiferromagnetic layer 11 and the first magnetic layer 1
2, the non-magnetic layer 13, the second magnetic layer 14, and the third magnetic layer 15 may be stacked in this order. That is, the order of the pinned layer and the free layer provided via the nonmagnetic layer 13 may be the order of the pinned layer and the free layer or the order of the free layer and the pinned layer from the substrate side.

Next, the materials used for the respective layers will be described. As the antiferromagnetic layer 11, FeMn, NiMn,
A material having a high Neel point and a large exchange coupling force with the first magnetic layer 12, such as NiO or FeO, is preferable. As the first magnetic layer 12, NiFe, NiFeCo alloy, or the like can be used. The nonmagnetic layer 13 is preferably made of Cu, which can easily realize a virtual bound state of conduction electrons, is close to the magnetic layer and the Fermi surface, and can obtain a large MR ratio. Second
For the magnetic layer 14, a material having a coercive force of 5 [Oe] or less is preferably used, and Ni ₈₀ having a coercive force of 5 [Oe] or less is used.
Fe ₂₀ and _{Ni y (Fe x Co 100-} x) 100-y
(50 ≦ x ≦ 90, 0 <y ≦ 100) or the like can be used. The third magnetic layer 15 to exchange coupling with the second magnetic layer 14, it is preferred that the coercive force is used 10 to 30 [Oe] of about material, coercivity is 10~30 [Oe] _Fe x C
_{o 100-x (0 ≦ x} ≦ 50), Ni y (Fe x Co
_100-x ) _100-y (0 ≦ x ≦ 50, 0 <y ≦ 2
0) etc. can be used.

The second magnetic layer 14 and the third magnetic layer 15 may be made of a material other than those described above as long as the coercive force of the third magnetic layer 15 is larger than that of the second magnetic layer 14.
Further, a non-magnetic layer may be provided between the second magnetic layer 14 and the third magnetic layer 15 as needed. Here, the nonmagnetic layer provided between the second magnetic layer 14 and the third magnetic layer 15 is a layer for controlling the exchange coupling force of both layers, and it is preferable that Cu is used for the same reason as the nonmagnetic layer 13.

In order to increase the crystallinity of the MR magnetic layer,
An underlayer may be provided between the substrate 5 and the MR magnetic layer. It is preferable that the underlayer has high resistance such as Ta and the (111) plane of the face-centered cubic lattice is preferentially oriented.

Next, the thickness of each of the above layers will be described.
The thickness of the antiferromagnetic layer 11 is preferably not less than 50 ° and not more than 2000 °. This is because if the thickness of the antiferromagnetic layer 11 is too small, the exchange magnetic field to the first magnetic layer 12 becomes insufficient. Conversely, if the thickness is too large, the substantial effect is not improved.

The thickness of each of the first magnetic layer 12, the second magnetic layer 14, and the third magnetic layer 15 is preferably not less than 20 ° and not more than 200 °. This is because if the thickness of the magnetic layer is less than 20 °, heat resistance and workability deteriorate, and if the thickness is more than 200 °, the substantial MR ratio does not improve. Also, when the MR magnetic layer becomes thicker, it becomes necessary to flow a large amount of current, and power consumption increases.

The thickness of the nonmagnetic layer 13 is 10 ° or more and 1
It is preferably not more than 00 °. If the thickness of the nonmagnetic layer is too small, the exchange coupling between the first magnetic layer 12 and the second magnetic layer 14 becomes too large. Conversely, if the thickness is too large, the proportion of conduction electrons flowing only inside this layer Is increased, and the MR change rate is reduced.

When a nonmagnetic layer for controlling the exchange coupling force is provided between the second magnetic layer 14 and the third magnetic layer 15, the thickness of the nonmagnetic layer is desirably 50 ° or less. If the thickness is more than this, the exchange coupling force becomes too small.

When an underlayer is provided between the substrate 5 and the MR magnetic layer, the thickness of the underlayer should be not less than 30.degree.
It is preferable that the angle is 0 ° or less. When the thickness of the underlayer is 30
と If the thickness is smaller, the effect of improving the crystallinity cannot be obtained,
Conversely, even if the thickness is more than 500 °, the effect thereof will level out.

(In the case of an induced ferri type structure) FIG. 1 (c)
Shows an MR magnetic layer having an induction ferrimagnetic structure, and a third magnetic layer 19, a second magnetic layer 18,
The non-magnetic layer 17 and the first magnetic layer 16 are stacked in this order. Here, the pair of the second magnetic layer 18 and the third magnetic layer 19 correspond to a soft layer, and the first magnetic layer 16 corresponds to a hard layer.

The order in which the layers are stacked is opposite to that shown in FIG. 1C, in which the first magnetic layer 16 and the non-magnetic layer 1
7, the second magnetic layer 18 and the third magnetic layer 19 may be stacked in this order. That is, the order of the soft layer and the hard layer provided via the nonmagnetic layer 17 may be the order of the soft layer and the hard layer or the order of the hard layer and the soft layer from the substrate side.

Next, the materials used for the respective layers will be described. Materials of the first magnetic layer 16 is not particularly limited, coercive force 10 [Oe] or more Co, PtCo alloy or _{Fe x Co 100-x (0} ≦ x ≦ 50),, Ni
_{y (Fe x Co 100-x} ) 100-y (0 ≦ x ≦ 5
0, 0 <y ≦ 20) and the like. here,
When information is recorded on the first magnetic layer 16, the first magnetic layer 1
The coercive force of No. 6 is preferably about the same as the coercive force of the third magnetic layer 19. The nonmagnetic layer 17 is preferably Cu, which can easily realize a virtual bound state of conduction electrons, is close to the Fermi surface with the magnetic layer, and can provide a large MR ratio. The second magnetic layer 18 is preferably made of a material having a coercive force of 5 [Oe] or less, and Ni ₈₀ Fe having a coercive force of 5 [Oe] or less.
₂₀ and _{Niy (Fe x Co 100-x} ) 100-y (5
0 ≦ x ≦ 90, 0 <y ≦ 100) and the like. The third magnetic layer 19 to exchange coupling with the second magnetic layer 18, it is preferred that the coercive force is used 10 to 30 [Oe] of about material, coercivity is 10~30 [Oe] _Fe x Co
_{100-x (0 ≦ x ≦} 50), Ni y (Fe x Co
_100-x ) _100-y (0 ≦ x ≦ 50, 0 <y ≦ 2
0) etc. can be used.

The second magnetic layer 18 and the third magnetic layer 19 may be made of a material other than those described above, as long as the coercive force of the third magnetic layer 19 is larger than that of the second magnetic layer 18.
Further, a non-magnetic layer may be provided between the second magnetic layer 18 and the third magnetic layer 19 as needed. Here, the nonmagnetic layer provided between the second magnetic layer 18 and the third magnetic layer 19 is a layer for controlling the exchange coupling force of both layers, and it is preferable to use Cu for the same reason as the nonmagnetic layer 17.

In order to improve the crystallinity of the MR magnetic layer,
An underlayer may be provided between the substrate 5 and the MR magnetic layer. It is preferable that the underlayer has a high resistance such as Ta and the (111) plane of the face-centered cubic lattice is oriented.

Next, the thickness of each layer will be described.
The thickness of each magnetic layer of the first magnetic layer 16, the second magnetic layer 18, and the third magnetic layer 19 is preferably 20 ° or more and 200 ° or less. This is because if the thickness of the magnetic layer is less than 20 °, heat resistance and workability deteriorate, and if the thickness is more than 200 °, the substantial MR ratio does not improve. Also, when the MR magnetic layer becomes thicker, it becomes necessary to flow a large amount of current, and power consumption increases.

The thickness of the non-magnetic layer 17 is 10 ° or more and 1
It is preferably not more than 00 °. If the thickness of the nonmagnetic layer is too small, the exchange coupling between the first magnetic layer 16 and the second magnetic layer 17 becomes too large. Conversely, if the thickness is too large, the proportion of conduction electrons flowing only inside this layer Is increased, and the MR change rate is reduced.

When a nonmagnetic layer for controlling the exchange coupling force is provided between the second magnetic layer 18 and the third magnetic layer 19, the thickness of the nonmagnetic layer is desirably 50 ° or less. If the thickness is more than this, the exchange coupling force becomes too small.

When an underlayer is provided between the substrate 5 and the MR magnetic layer, the thickness of the underlayer should be not less than 30.degree.
It is preferable that the angle is 0 ° or less. When the thickness of the underlayer is 30
と If the thickness is smaller, the effect of improving the crystallinity cannot be obtained,
Conversely, even if the thickness is more than 500 °, the effect thereof will level out.

(Recording / Reproducing Method) Next, a recording / reproducing method of the magnetic thin film memory of the present invention will be described.

First, a case where information is recorded on one magnetic thin film memory element will be described with reference to FIGS. 2 (a) and 2 (b). FIGS. 2A and 2B show a case where information is recorded on a spin-valve type magnetic thin film memory element (a case where information is recorded on a free layer). 32 is a non-magnetic layer, and 3 is a non-magnetic layer.
Reference numerals 3 and 34 denote a second magnetic layer and a third magnetic layer corresponding to the free layer. Here, the axes of easy magnetization of the first magnetic layer 31, the second magnetic layer 33, and the third magnetic layer 34 are all parallel, and these easy axes of magnetization are set in a direction orthogonal to the write line 21. Reference numerals 22 and 23 denote magnetic fields generated by a write current flowing through the write line 21, and the direction of the magnetic field is determined by the direction of the write current flowing through the write line 21. The magnetization direction of the second magnetic layer 33 and the third magnetic layer 34 corresponding to the free layer is set by the magnetic field 22 or 23 generated by the write current, and the binary “0” is set in the magnetization direction. In FIG. 2A, a magnetic field (a clockwise magnetic field on the paper) 22 generated by a write current flowing through the write line 21 is used. The second magnetic layer 33 and the third magnetic layer 34 are oriented in the direction opposite to the magnetization direction of the first magnetic layer 31 (leftward on the paper).
Magnetized. On the other hand, in (b), the magnetic field (counterclockwise magnetic field) 23 generated by the write current flowing through the write line 21 divides the second magnetic layer 33 and the third magnetic layer 34 into the first magnetic layer 34. The layer 31 is magnetized in the same direction as the magnetization direction (rightward on the paper). Here, the magnetic field generated by the write current flowing through the write line 21 is made larger than the coercive force of the second magnetic layer 33 and the third magnetic layer 34 corresponding to the free layer. Even if the first magnetic layer 31 corresponding to the pinned layer undergoes magnetization reversal when the magnetic field 22 or the magnetic field 23 is applied, the state returns to the state before the application of the magnetic field if the magnetic field is removed. May be reversed by a recording magnetic field (magnetic field 22 or magnetic field 23).

Next, a case where the information recorded as described above is reproduced will be described with reference to FIGS. FIG. 2C shows the magnetic field 22 shown in FIG.
FIG. 2 (d) shows a case where the information recorded in step (1) is reproduced.
Shows a case where information recorded by the magnetic field 23 shown in FIG.

When reproducing information recorded by the magnetic field 22 or the magnetic field 23, a pulse current (hereinafter referred to as a reproduction current) smaller than the write current is applied to the write line 21 while a read current is applied to the read line 25. Flow in a certain direction. Here, the magnetic field 24 generated by the reproduction current flowing through the write line 21 is set to be larger than the coercive force of the second magnetic layer 33 and smaller than the coercive force of the third magnetic layer 34. The direction of the magnetic field 24 as the reproducing magnetic field is the first direction.
The magnetization direction of the first magnetic layer may be the same as or opposite to the magnetization direction of the magnetic layer, but the intensity is set so that the magnetization direction of the first magnetic layer is not reversed when the magnetic field 24 is applied.

Note that the direction in which the reproduction current flows may be set to a direction in which a clockwise magnetic field is generated on the paper surface or may be set to a direction in which a counterclockwise magnetic field is generated. ),
In (d), the direction is set so that the counterclockwise magnetic field 24 is generated.

In the case of FIG. 2C, the magnetic field 22 at the time of recording information and the magnetic field 24 generated by the reproducing current are in opposite directions.
3, the magnetization direction is reversed, and the magnetic thin film memory element MR
The resistance value of the magnetic layer decreases. As a result, a voltage change (voltage rise) occurs on the output side of the read line 25 through which the read current flows. On the other hand, in the case of (d), a magnetic field 23 when information is recorded and a magnetic field 24 generated by a reproduction current
Are the same direction, so that when a reproducing current is passed, the magnetization direction of the second magnetic layer 33 does not reverse, and the resistance value of the MR magnetic layer, which is a magnetic thin film memory element, does not change. Accordingly, no voltage fluctuation occurs on the output side of the read line 25 through which the read current flows.

Here, the relationship between the reproduction current flowing through the write line 21 and the voltage on the output side of the read line 25 is shown in FIG. When the reproduction current shown in FIG.
When the magnetization direction of the magnetic layer 33 is reversed, a voltage fluctuation occurs on the output side of the read line 25 as shown in FIG.
When the magnetization direction of the second magnetic layer 33 is not reversed, (c)
As shown in (1), no voltage fluctuation occurs on the output side of the read line 25.

In FIG. 2C and FIG. 2D, when the reproducing current is set in the direction in which the clockwise magnetic field is generated,
In (c), the magnetization direction of the second magnetic layer 33 does not reverse, and the resistance value of the MR magnetic layer, which is a magnetic thin film memory element, does not change. In (d), the magnetization direction of the second magnetic layer 33 reverses. However, the resistance value of the MR magnetic layer, which is a magnetic thin film memory element, increases. Therefore, only in the case of (d), the read line 25
Causes voltage fluctuation (voltage drop).

That is, if the direction in which the reproduction current flows is constant, a voltage fluctuation occurs only when the magnetization direction of the second magnetic layer 33 is either one, and when the magnetization direction is reversed, the voltage fluctuation occurs. Since this does not occur, the magnetization direction of the second magnetic layer 33 can be determined as the presence or absence of a voltage change.

As described above, when recording information,
"0" and "1" are made to correspond to the magnetization direction of the free layer, and a write current in a direction corresponding to information to be written is written to the write line 21.
When information is recorded (by setting the magnetization direction of the free layer) and the recorded information is reproduced, the write current is applied to the read line 25 while the read current is applied to the read line 25.
The recorded information can be reproduced by supplying a reproduction current to the read line and detecting the presence or absence of a voltage change in the read line 25 at that time.

In the magnetic thin film memory element of the present invention, when the magnetization direction of the second magnetic layer 33 is reversed at the time of reproduction, that is, when a reproduction current is applied to the write line 21, after reproduction, that is, When the reproduction current is turned off and the application of the magnetic field by the reproduction current is stopped, the magnetization direction of the inverted second magnetic layer 33 becomes
The state before the reproduction is restored by the exchange magnetic field from the third magnetic layer 34. Therefore, by using the magnetic thin film memory element of the present invention, the recorded information can be reproduced without destroying the recorded information.

Next, the case of recording on the induction ferrimagnetic thin film memory element (the case of recording on the hard layer) will be described with reference to FIGS. In the induction ferrimagnetic thin film memory device shown in FIG.
Corresponds to the hard layer, and the second magnetic layer 33 and the third magnetic layer 34
Corresponds to the soft layer. Here, the first magnetic layer 31, the second magnetic layer 31,
The axes of easy magnetization of the magnetic layer 33 and the third magnetic layer 34 are all parallel to each other as in the case of the spin-valve type, and
Are set in a direction perpendicular to the direction.

In the case of the induction ferrimagnetic thin film memory element, the magnetization direction of the first magnetic layer 31 corresponding to the hard layer changes in the direction of the magnetic field due to the magnetic field 22 or 23 generated by the write current flowing through the write line 21. It is set, and two values “0” and “1” are assigned to the magnetization direction.

In FIG. 4A, a magnetic field (clockwise magnetic field) 22 generated by a write current flowing through the write line 21 causes the first magnetic layer 31 to move in the direction of the magnetic field 22 (on the paper). To the left). on the other hand,
In (b), a magnetic field generated by a write current flowing through the write line 21 (a counterclockwise magnetic field on the paper)
At 23, the first magnetic layer 31 is magnetized in the direction of the magnetic field 23 (rightward on the paper).

Since the magnetic field generated by the write current flowing through the write line 21 is larger than the coercive force of the first magnetic layer 31 corresponding to the hard layer, the second magnetic layer 33 corresponding to the soft layer and the third magnetic layer Layer 34 is also magnetized in the direction of the magnetic field.

Next, a case where the information recorded as described above is reproduced will be described with reference to FIG. FIGS. 5A and 5B show a case where information recorded by the magnetic field 22 shown in FIG. 4A is reproduced, and FIGS.
Shows a case where information recorded by the magnetic field 23 shown in FIG. 4B is reproduced.

When reproducing the information recorded by the magnetic field 22 or the magnetic field 23, a current (which is smaller than the write current in the write line 21 and switches the direction in which the current flows in a time-division manner while the read current flows in the read line 25). Hereinafter, it is referred to as a reproduction change current). Here, a magnetic field 24a generated by a reproduction change current flowing through the write line 21
And the magnetic field 24b are larger than the coercive force of the second magnetic layer 33,
The coercive force of the third magnetic layer 34 is set to be smaller than the coercive force.

5A and 5B, when the magnetic field 24a is applied, the magnetization direction of the first magnetic layer 31 and the magnetization direction of the second magnetic layer 33 are opposite to each other. The resistance value of the MR magnetic layer, which is a thin film memory element, increases. On the other hand, when the magnetic field 24b is applied, the first magnetic layer 3
Since the magnetization direction of 1 and the magnetization direction of the second magnetic layer 33 are in the same direction, the resistance value of the MR magnetic layer, which is a magnetic thin film memory element, becomes small. Therefore, when the magnetic field changes from the magnetic field 24a to the magnetic field 24b, the resistance of the MR magnetic layer changes from a high resistance to a low resistance. As a result, when the magnetic field changes, the voltage on the output side of the read line 25 through which the read current flows increases.

In the case of FIGS. 5C and 5D, when the magnetic field 24a is applied, the magnetization direction of the first magnetic layer 31 and the magnetization direction of the second magnetic layer 33 are in the same direction. The resistance value of the MR magnetic layer, which is a thin film memory element, becomes smaller.
On the other hand, when the magnetic field 24b is applied, the magnetization direction of the first magnetic layer 31 and the magnetization direction of the second magnetic layer 33 are opposite, so that the resistance value of the MR magnetic layer, which is a magnetic thin film memory element, is large. Become. Therefore, when the magnetic field changes from the magnetic field 24a to the magnetic field 24b, the resistance of the MR magnetic layer changes from low resistance to high resistance. As a result, when the magnetic field changes, the voltage on the output side of the read line 25 through which the read current flows drops.

Here, the relationship between the reproduction change current flowing through the write line 21 and the voltage on the output side of the read line 25 is shown in FIG. When the reproduction change current shown in FIG. 6A flows and the current direction changes in accordance with the magnetization direction of the first magnetic layer 31, the voltage on the output side of the read line 25 increases ((b )) Or descend ((c)). Therefore, in the reproduction change current, when the direction of the current changes, whether the voltage on the output side of the read line 25 rises or falls is detected, so that the magnetization direction of the first magnetic layer 31 is changed. You can judge.

As described above, when recording information,
“0” and “1” are assigned to the magnetization direction of the hard layer, and a write current in a direction corresponding to the information to be written is applied to the write line 21.
When the information is recorded (by setting the magnetization direction of the hard layer) and the recorded information is reproduced, the read current is applied to the read line 25 while the write line 21 is supplied.
The recorded information can be reproduced by supplying a reproduction change current to the read line 25 and detecting the rise or fall of the voltage on the read line 25 at that time. The reproduction change current is
The magnetic field may be set so that the magnetic field changes in the order of the magnetic field 24b and the magnetic field 24a.

In the magnetic thin film memory element of the present invention, after the reproduction, that is, when the reproduction change current is turned off and the application of the magnetic field by the reproduction change current is stopped, the magnetization direction of the second magnetic layer 33 becomes the third magnetic layer. Due to the exchange magnetic field from the magnetic layer 34, the magnetization direction of the third magnetic layer 34 returns to the same direction as the magnetization direction of the first magnetic layer. Therefore, the magnetic thin film memory element of the present invention has a low resistance when no magnetic field is applied, so that when a memory is configured, heat generation and power loss due to heat generation can be reduced.

Next, a case where information is written to the magnetic thin film memory elements arranged in a matrix will be described.

FIG. 7 shows a plan view (a) of the magnetic thin film memory and an AA ′ sectional view (b) thereof.
MR magnetic films, which are magnetic thin film memory elements, are arranged in a matrix at portions where the write assist lines 2 and 53 are orthogonal to the write assist lines 61, 62 and 63. Here, the magnetic thin film memory elements are connected in series in the read auxiliary line direction to form a read line. For example, in the portion shown in the AA ′ section, the portion where the magnetic thin film memory elements 41, 42, 43 are connected in series becomes the read line 2.

As described above, when the magnetic thin film memory elements are arranged in a matrix, a write current sufficient to change the magnetization direction of the second magnetic layer of the magnetic thin film memory element was applied to the write line. In this case, the first magnetic layer and the second magnetic layer of the magnetic thin film memory arranged along the write line through which the write current has flowed are all magnetized in the direction of the magnetic field generated by the write current. That is, writing is all performed on the magnetic thin-film memories arranged along the write line through which the write current has flowed. Therefore, when the magnetic thin film memory elements are arranged in a matrix,
It is not possible to direct only the magnetization direction of some of the magnetic thin-film memory elements to a desired magnetization direction with only the current flowing through the write lines, that is, to write information only to some of the elements.

FIGS. 8 and 9 show a case where information is recorded only in a part of the magnetic thin film memory elements arranged in a matrix by applying a current to both the write line and the write auxiliary line. This will be described with reference to FIG.

In FIG. 8A, Iw1 indicates a write current flowing through the write line 50, and Iw indicates a write auxiliary current flowing through the write auxiliary line 60. And Hw
1 indicates a write magnetic field generated by the write current Iw1, and Hw indicates a write auxiliary magnetic field generated by the write auxiliary current Iw. Here, in the case of a memory element for recording information in the third magnetic layer (free layer), the write magnetic field Hw1 and the write auxiliary magnetic field Hw are both smaller than the coercive force of the third magnetic layer of the magnetic thin film memory element. The magnetization direction of the third magnetic layer cannot be changed only by the magnetic field. However, since the composite magnetic field H1 of the write magnetic field Hw1 and the write auxiliary magnetic field Hw is larger than the coercive force of the third magnetic layer, when both the write current Iw1 and the write auxiliary current Iw are passed, the magnetization of the third magnetic layer is reduced. The direction can be changed, that is, information can be recorded. Note that the second magnetic layer is also magnetized in the same direction as the magnetization direction of the third magnetic layer.

FIG. 8B shows the write magnetic field Hw1, the write auxiliary magnetic field Hw, the composite magnetic field H1, and the axis of easy magnetization 40a of the third magnetic layer 40. Here, since the synthetic magnetic field H1 is larger than the coercive force of the second magnetic layer 2, the third magnetic layer 40
Is magnetized by the synthetic magnetic field H1, and its magnetization direction B1
Is the direction of a component parallel to the easy axis 40a of the synthetic magnetic field H1. Note that the write magnetic field Hw1 generated by the write current Iw1 depends on the axis of easy magnetization 40a of the third magnetic layer 40.
And the auxiliary write magnetic field Hw generated by the auxiliary write current Iw is the axis of easy magnetization 4 of the third magnetic layer 40.
Since it is almost perpendicular to 0a, the magnetization direction B1 is determined by the write magnetic field Hw1, that is, the write current Iw1.

FIG. 9A shows the write current Iw1 of FIG.
And the write current Iw2 flows in the opposite direction. Therefore, the direction of the generated write magnetic field Hw2 is also opposite to the direction of the write magnetic field Hw1 in FIG. Therefore, as shown in FIG. 8B, the magnetization direction B2 of the third magnetic body 40 is also opposite to the magnetization direction B1 of FIG.

As described above, when the magnetic thin film memory elements are arranged in a matrix, current is applied only to the write line and the write auxiliary line passing through the portion of the magnetic thin film memory element where information is to be recorded. Information can be recorded only in a part of the magnetic thin film memory element. or,
Information (“0” or “1”) recorded as the magnetization direction of the magnetic thin film memory element can be freely set according to the direction of the current flowing through the write line.

Also, when information is recorded on the hard layer (first magnetic layer), the information can be recorded in the same manner as described above by adjusting the magnitude of the write current and the write auxiliary current.

On the other hand, when reading information written in the magnetic thin film memory elements arranged in a matrix, a read current is applied to a read line connected to the magnetic thin film memory element to be read, and the magnetic thin film memory is read. By supplying a reproduction current or a reproduction change current to a write line passing through the element part, recorded information can be reproduced in the same manner as in the case of one element.

In the above description, information is recorded by applying a current to the write line and the auxiliary write line, but the information is recorded even if no current is applied to the read line instead of the auxiliary write line without providing the auxiliary write line. can do.

Example 1 In this example, the magnetic thin film memory element was an MR magnetic layer having a spin valve type structure (FIG. 1A,
(Refer to (b)).

In the present embodiment, Ni ₈₀ Fe ₁₅ C
The third magnetic layer 15 of thickness 50Å consisting o _{5, Ni 80} F
second magnetic layer 14 of thickness 50Å consisting e _20, non-magnetic layer thickness 30Å of Cu layer _13, Ni 80 first magnetic layer 12 of thickness 100Å consisting _{Fe 20,} made of FeMn layer thickness 200Å anti of A ferromagnetic layer 11 is laminated to form a magnetic thin-film memory element, coated with an insulating layer 3 made of Al ₂ O ₃ and having a thickness of 1000 °, and then processed to a size of 5 μm × 20 μm to form one magnetic thin-film memory element. Produced. Further, a readout electrode 2, an insulating layer 3, and a write line 4 were sequentially laminated and processed to produce a magnetic thin film memory.

The magnetic thin film memory element is formed while applying a magnetic field so that the axis of easy magnetization of each magnetic layer is oriented in the longitudinal direction of the element, and the write line is wired in a direction perpendicular to the axis of easy magnetization. ing. The magnetic thin film memory element was formed by DC sputtering under the following film forming conditions, and the insulating layer was formed by RF sputtering.

Ultimate pressure 5 × 10 ⁻⁵ Pa Ar gas 10 SCCM Film formation pressure 0.5 Pa Input power 100 W Film formation rate 0.5 nm / sec It may be formed by molecular beam epitaxy (MBE) or ion beam sputtering (IBS).

FIG. 10 shows the case where the magnetic thin film memory element is ± 30.
3 shows a magnetization curve of [Oe]. In this magnetic field range, the first
The magnetic layer does not cause magnetization reversal. It can be seen that the hysteresis loop of the second magnetic layer 17 has shifted due to the exchange magnetic field from the third magnetic layer 16. Further, from the same figure, the coercive force of the second magnetic layer is about 3 Oe, and the coercive force of the third magnetic layer is about 20 Oe.
It can be seen that it is.

Hereinafter, in the order of P1 to P10 on the magnetization curve,
The change in the magnetization direction of the second magnetic layer and the third magnetic layer will be described.

P1 to P3: a magnetic field in a direction opposite to the magnetization directions of the second and third magnetic layers (hereinafter, the magnetization directions of the second and third magnetic layers in P1 are referred to as forward directions). When the magnetic field is increased, the magnetization reversal occurs only in the second magnetic layer at about 8 [Oe] (P2, P3).
Therefore, at P3, the magnetization direction of the second magnetic layer is in the opposite direction, and the magnetization direction of the third magnetic layer is in the forward direction. The coercive force of only the second magnetic layer is 3 [Oe],
Due to the exchange magnetic field from the third magnetic layer,
The second magnetic layer does not cause magnetization reversal until about 8 [Oe].

P3 to P5: When the magnetic field is further increased after the magnetization reversal of the second magnetic layer, about 20 [Oe]
Then, the third magnetic layer also causes magnetization reversal (P4, P5). Therefore, at P5, the magnetization direction of the second magnetic layer is also changed to the third magnetic layer.
The magnetization direction of the magnetic layer is also in the opposite direction. When the applied magnetic field is removed between P3 and P4, that is, before the third magnetic layer causes the magnetization reversal, the magnetization direction of the second magnetic layer becomes the third magnetic layer.
By the exchange coupling force with the magnetic layer, the magnetization direction of the third magnetic layer,
That is, it returns to the forward direction.

P5 to P8: After the magnetization reversal of the second magnetic layer and the third magnetic layer, the magnetic field in the reverse direction is removed, and the magnetic field in the forward direction is applied.
At [Oe], first, only the second magnetic layer undergoes magnetization reversal (P7, P8). Therefore, at P8, the magnetization direction of the second magnetic layer is in the forward direction, and the magnetization direction of the third magnetic layer is in the reverse direction. Note that, due to the exchange magnetic field from the third magnetic layer, the second magnetic layer does not cause magnetization reversal until about 8 [Oe].

P8 to P10: After the reversal of the magnetization of the second magnetic layer, when the magnetic field in the forward direction is further increased, about 2
At 0 [Oe], the third magnetic layer also causes magnetization reversal (P9, P9
10). Therefore, at P10, both the magnetization direction of the second magnetic layer and the magnetization direction of the third magnetic layer are in the forward direction.
When the applied magnetic field is removed between P8 and P9, that is, before the third magnetic layer causes the magnetization reversal, the magnetization direction of the second magnetic layer is changed by the exchange coupling force with the third magnetic layer. The magnetization direction of the layer returns to the opposite direction.

As can be seen from the above description, the magnetic field generated by the reproduction current is larger than 8 [Oe] and 20 [Oe].
If a smaller magnetic field, that is, a magnetic field stronger than the magnetic field causing the magnetization reversal of the second magnetic layer and weaker than the magnetic field causing the magnetization reversal of the third magnetic layer in the stacked state, the information is reproduced without discarding. be able to.

Here, a write current of 30 mA is applied to the write line to magnetize the second magnetic layer and the third magnetic layer in the forward direction, and then a read current of 10 mA for generating a forward magnetic field is applied to the write line. In addition, no voltage fluctuation occurred in the read line.

Next, 30 lines are applied to the write line in the direction opposite to the above.
After applying a write current of mA to magnetize the second magnetic layer and the third magnetic layer in the reverse direction, a forward magnetic field of 10 m is generated.
When the read current of A was passed through the write line, only the second magnetic layer caused magnetization reversal, and a voltage fluctuation of 15 mV occurred in the read line.

Further, the same result was obtained even when reproduction was performed a plurality of times, and it was confirmed that information could be reproduced in a non-destructive manner.

(Embodiment 2) In this embodiment, the magnetic thin film memory element is an MR magnetic layer having an induction ferri structure (FIG. 1A,
(C)) is an example of a magnetic thin film memory in the case of (1).

In this embodiment, Ni ₈₀ Fe ₁₅ C
The third magnetic layer 19 of thickness 50Å consisting o _{5, Ni 80} F
e _{20 a} second magnetic layer 18 having a thickness of 50 °, a non-magnetic layer 17 having a thickness of 30 ° made of Cu, Ni ₈₀ Fe ₁₅ C
The first magnetic layer 16 of thickness 50Å consisting o _{5, Al} 2 _{O 3}
After laminating an insulating layer 3 having a thickness of 1000 ° and processing into a size of 5 μm × 20 μm, one magnetic thin film memory element was manufactured. Further, a readout electrode 2, an insulating layer 3, and a write line 4 were sequentially laminated and processed to produce a magnetic thin film memory.

The magnetic thin film memory element is formed while applying a magnetic field so that the axis of easy magnetization of each magnetic layer is oriented in the longitudinal direction of the element, and the write line is wired in a direction perpendicular to the axis of easy magnetization. ing. The magnetic thin film memory element was formed by DC sputtering under the same film forming conditions as in Example 1.

The coercive force of the first magnetic layer and the third magnetic layer is:
Both were about 20 [Oe], and the magnetization reversal of the second magnetic layer occurred when a magnetic field of about 8 [Oe] was applied in the stacked state.

Here, a write current of 30 mA is applied to the write line to magnetize the first magnetic layer, the second magnetic layer, and the third magnetic layer in the forward direction. Then, a forward magnetic field of 10 mA is generated.
When the read current was passed through the write line, no voltage fluctuation occurred in the read line.

Next, 30 lines are applied to the write line in the direction opposite to the above.
When a write current of mA is passed to magnetize the first, second, and third magnetic layers in the reverse direction, a read current of 10 mA, which produces a forward magnetic field, is applied to the write line.
Only the magnetic layer causes magnetization reversal, and the read line has a voltage of 18 mV.
Voltage fluctuation occurred.

Further, it was confirmed that the magnetic thin film memory element was always in the low resistance state when the reproducing current was not passed.

[0110]

As described above, in the magnetic thin film memory of the present invention, when information is recorded on the free layer of the spin valve type or the soft layer of the induction ferri type, the recorded information is reproduced in a non-destructive manner. be able to. Further, the writing current can be reduced, and the power consumption during writing can be reduced.

Further, since the structure is simple, it is possible to provide a magnetic thin film memory element which is easy to manufacture and inexpensive.

On the other hand, when information is recorded on the induction ferri-type hard layer, the magnetic thin film memory element always has a low resistance in the state where no magnetic field is applied. Useless power consumption and heat generation in a magnetic thin film memory element to which a magnetic field due to a reproduction change current is not applied, that is, an element in which reproduction is not performed, can be suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a magnetic thin film memory and a memory element according to the present invention.

FIG. 2 is an explanatory diagram showing a recording / reproducing method for recording information on a free layer or a soft layer of a magnetic thin film memory element.

FIG. 3 is a waveform diagram showing a reproduction current flowing through a write line and a voltage on an output side of a read line.

FIG. 4 is an explanatory diagram showing a recording method when information is recorded on a hard layer of a magnetic thin film memory element.

FIG. 5 is an explanatory view showing a reproducing method when information is recorded on a hard layer of the magnetic thin film memory element.

FIG. 6 is a waveform diagram showing a reproduction change current flowing through a write line and a voltage on an output side of a read line.

FIG. 7 is a plan view and a sectional view showing a magnetic thin film memory according to the present invention.

FIG. 8 is an explanatory diagram showing a case where information is recorded in a magnetic thin film memory element arranged in a matrix form.

FIG. 9 is an explanatory diagram showing a case where information is recorded in a magnetic thin film memory element arranged in a matrix form.

FIG. 10 is a graph showing a magnetization curve of the magnetic thin film memory element according to the present invention.

FIG. 11 is a perspective view showing a conventional magnetic thin film memory using AMR.

FIG. 12 is an explanatory diagram showing a recording / reproducing method of a conventional magnetic thin film memory using GMR.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 MR magnetic layer 2 read line 3 insulating layer 4 write line 5 substrate 11 antiferromagnetic layer 12 first magnetic layer (pinned layer) 13 nonmagnetic layer 14 second magnetic layer (free layer) 15 third magnetic layer (free layer) 16) First magnetic layer (hard layer) 17 Non-magnetic layer 18 Second magnetic layer (soft layer) 19 Third magnetic layer (soft layer) 22, 23 Magnetic field (recording magnetic field) 24, 24a, 24b Magnetic field (reproducing magnetic field)

Continued on the front page (72) Inventor Satoru Araki 1-1-13 Nihonbashi TDC Corporation, Chuo-ku, Tokyo (72) Inventor Osamu Shinoura 1-13-1 Nihonbashi 1-chome, Chuo-ku, Tokyo TDK Corporation (56) References WO 95/22820 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11C 11/14-11/15 H01L 27/10 H01L 43/08 H01F 10 / 32

Claims (7)

(57) [Claims] A first magnetic layer, a non-magnetic layer, a second magnetic layer, and a third magnetic layer stacked in this order or in the reverse order; A magnetic thin film memory element, wherein the coercive force of the magnetic layer is larger than the coercive force of the second magnetic layer, and the second magnetic layer and the third magnetic layer are in direct contact and exchange-coupled. 2. A magnetic thin-film memory element for recording information as a magnetization direction, a read line for detecting a change in resistance of the magnetic thin-film memory element, and a write line for applying a magnetic field to the magnetic thin-film memory element. In the magnetic thin film memory, the magnetic thin film memory element comprises a thin film in which a first magnetic layer, a nonmagnetic layer, a second magnetic layer, and a third magnetic layer are stacked in this order or in the reverse order. A magnetic thin film memory wherein the coercive force of the first magnetic layer and the third magnetic layer is larger than the coercive force of the second magnetic layer, and the second magnetic layer and the third magnetic layer are in direct contact and exchange-coupled. . 3. The magnetic thin film memory according to claim 2, wherein a magnetic field applied to the magnetic thin film memory element at the time of writing is larger than the coercive force of the third magnetic layer and smaller than the coercive force of the first magnetic layer. Wherein the magnetic field applied to the magnetic thin-film memory element at the time of reading is a magnetic field larger than the coercive force of the second magnetic layer in a stacked state and smaller than the coercive force of the third magnetic layer. Thin film memory. 4. The magnetic thin film memory according to claim 2, wherein a magnetic field applied to the magnetic thin film memory element at the time of writing is larger than the coercive force of the first magnetic layer and the third magnetic layer, and at the time of reading, the magnetic thin film is A magnetic thin film memory, wherein a magnetic field applied to the memory element is larger than a coercive force of the second magnetic layer in a stacked state and smaller than a coercive force of the first magnetic layer and the third magnetic layer. 5. A magnetic thin film memory device comprising an antiferromagnetic layer, a first magnetic layer, a nonmagnetic layer, a second magnetic layer, and a third magnetic layer stacked in this order or in the reverse order . A magnetic thin film memory element, wherein the coercive force of the magnetic layer is larger than the coercive force of the second magnetic layer, and the second magnetic layer and the third magnetic layer are exchange-coupled. 6. A magnetic thin film memory element for recording information as a magnetization direction, a read line for detecting a change in resistance value of the magnetic thin film memory element, and a write line for applying a magnetic field to the magnetic thin film memory element. In the magnetic thin film memory, the magnetic thin film memory element includes an antiferromagnetic layer,
Magnetic layer, nonmagnetic layer, a second magnetic layer, in this order or the third magnetic layer
Alternatively, it is made up of thin films laminated in the reverse order , and the coercive force of the third magnetic layer is larger than the coercive force of the second magnetic layer, and the second magnetic layer and the third magnetic layer are exchange-coupled. Characterized magnetic thin film memory. 7. The magnetic thin film memory according to claim 6, wherein a magnetic field applied to the magnetic thin film memory element at the time of writing is larger than the coercive force of the third magnetic layer, and applied to the magnetic thin film memory element at the time of reading. A magnetic thin film memory, wherein the magnetic field is larger than the coercive force of the second magnetic layer in the stacked state and smaller than the coercive force of the third magnetic layer.