JP5075802B2

JP5075802B2 - Magnetic memory cell and magnetic random access memory

Info

Publication number: JP5075802B2
Application number: JP2008313679A
Authority: JP
Inventors: 路彦山ノ内; 宏昌高橋; 純早川
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2008-12-09
Filing date: 2008-12-09
Publication date: 2012-11-21
Anticipated expiration: 2028-12-09
Also published as: JP2010140973A

Description

本発明は、不揮発性磁気メモリセル及びそれを用いたランダムアクセスメモリに関するものである。 The present invention relates to a nonvolatile magnetic memory cell and a random access memory using the same.

近年、スピントランスファートルクにより磁気情報の書き込みを行う不揮発性磁気メモリが注目されており、例えば米国特許第５，６９５，８６４号明細書、米国特許第６，２５６，２２３号明細書あるいは特開２００２−３０５３３７号公報に開示されている。この書き込み方式を利用した不揮発性磁気メモリは、磁気抵抗効果素子に直接電流を流すことにより強磁性記録層の磁化方向を回転させて磁気情報を書き込む。磁気抵抗効果素子は、強磁性固定層と強磁性記録層の磁化方向がなす角度に応じた抵抗値を示すので、記憶情報の読み出しは、書き込み電流より小さな電流で磁気抵抗効果素子の抵抗を検出することにより行う。 In recent years, attention has been focused on non-volatile magnetic memories for writing magnetic information by spin transfer torque. For example, US Pat. No. 5,695,864, US Pat. -305337. A nonvolatile magnetic memory using this writing method writes magnetic information by rotating the magnetization direction of the ferromagnetic recording layer by passing a current directly through the magnetoresistive element. The magnetoresistive effect element shows a resistance value corresponding to the angle formed by the magnetization direction of the ferromagnetic pinned layer and the ferromagnetic recording layer. Therefore, when reading stored information, the resistance of the magnetoresistive effect element is detected with a current smaller than the write current. To do.

スピントランスファートルクで書き込みを行う場合、書き込み電流の大きさはダンピング定数、磁化の大きさの２乗、強磁性記録層の体積にほぼ比例する。また、記憶されている情報の熱安定性の指標Ｅ／ｋＴは磁化の大きさ、異方性磁界、強磁性記録層の体積に比例し、この値が小さいと予期せずに記憶情報が書き換わる確率が増加する。 When writing is performed with the spin transfer torque, the magnitude of the write current is substantially proportional to the damping constant, the square of the magnitude of the magnetization, and the volume of the ferromagnetic recording layer. The thermal stability index E / kT of stored information is proportional to the magnitude of magnetization, the anisotropic magnetic field, and the volume of the ferromagnetic recording layer. If this value is small, the stored information is written unexpectedly. The probability of switching increases.

不揮発性磁気メモリの大容量化によりメモリセルの膜面内方向の寸法が縮小すると、強磁性記録層の体積が小さくなるために書き込み電流は小さくなる。一方で、記録情報を保持するために充分なＥ／ｋＴを確保することが困難になる。その結果、記録情報の読み出しの際に流す電流により記憶情報が書き換わる誤書き込みが生じやすくなる。逆に強磁性記録層の膜厚を増加させてＥ／ｋＴを確保すると、書き込み電流も増加してしまい書き込みが困難になる。したがって、書き込み電流を増加させずに誤書込みを低減する方法として、強磁性記録層の体積に依存しない方法が求められている。このような状況の中で、強磁性記録層の体積を変えずに書き込み電流を低減可能な方法が特開２００８−４９５２号公報に開示されている。この方法では書き込みの際に強磁性記録層を加熱することにより磁化を低下させ、書き込み電流を低減する。 When the size of the memory cell in the in-plane direction is reduced due to the increase in capacity of the nonvolatile magnetic memory, the volume of the ferromagnetic recording layer is reduced, so that the write current is reduced. On the other hand, it becomes difficult to secure a sufficient E / kT for holding recorded information. As a result, erroneous writing in which stored information is rewritten due to a current that flows when reading recorded information is likely to occur. Conversely, if E / kT is secured by increasing the film thickness of the ferromagnetic recording layer, the write current also increases and writing becomes difficult. Therefore, there is a demand for a method that does not depend on the volume of the ferromagnetic recording layer as a method of reducing erroneous writing without increasing the write current. In such a situation, a method capable of reducing the write current without changing the volume of the ferromagnetic recording layer is disclosed in Japanese Patent Application Laid-Open No. 2008-4952. In this method, the magnetization is lowered by heating the ferromagnetic recording layer during writing, and the writing current is reduced.

米国特許第５，６９５，８６４号明細書US Pat. No. 5,695,864 米国特許第６，２５６，２２３号明細書US Pat. No. 6,256,223 特開２００２−３０５３３７号公報JP 2002-305337 A 特開２００８−４９５２号公報JP 2008-4952 A

不揮発性磁気メモリの大容量化に伴ってメモリセルのサイズが縮小されるため、読み出しによる誤書き込みを低減することが必須となる。本発明は、書き込み電流を増加させることなく、このような要請に応えることが可能な不揮発性磁気抵抗メモリを提供することを目的とする。 Since the size of the memory cell is reduced as the capacity of the nonvolatile magnetic memory is increased, it is essential to reduce erroneous writing due to reading. An object of the present invention is to provide a nonvolatile magnetoresistive memory capable of meeting such a demand without increasing the write current.

本発明のトンネル磁気抵抗効果素子は、絶縁膜と、絶縁膜を挟んで設けられた強磁性記録層と強磁性固定層とを有し、強磁性記録層は非磁性導電層を挟んで設けられた第一の強磁性膜と第二の強磁性膜からなり、第二の強磁性膜はフェリ磁性体である。 The tunnel magnetoresistive element of the present invention has an insulating film, a ferromagnetic recording layer provided between the insulating films, and a ferromagnetic fixed layer. The ferromagnetic recording layer is provided between the nonmagnetic conductive layers. The first ferromagnetic film and the second ferromagnetic film are made of a ferrimagnetic material.

フェリ磁性体は、角運動量補償温度が読み出し動作時の温度近傍にあって書き込み動作時には前記角運動量補償温度より高温になる。また、フェリ磁性体の読み出し電流通電時の温度におけるダンピング定数は、書き込み電流通電時の温度におけるダンピング定数よりも大きい。 In the ferrimagnetic material, the angular momentum compensation temperature is in the vicinity of the temperature during the read operation, and becomes higher than the angular momentum compensation temperature during the write operation. Further, the damping constant at the temperature when the read current is supplied to the ferrimagnetic material is larger than the damping constant at the temperature when the write current is supplied.

更に、第一の強磁性膜と第二の強磁性膜の磁化は交換結合しており、角運動量補償温度より高い温度、すなわち書き込み動作時の温度、において第一の強磁性膜と第二の強磁性膜の磁化方向が互いに逆方向である。 Further, the magnetizations of the first ferromagnetic film and the second ferromagnetic film are exchange-coupled, and the first ferromagnetic film and the second ferromagnetic film are in a temperature higher than the angular momentum compensation temperature, that is, the temperature during the writing operation. The magnetization directions of the ferromagnetic film are opposite to each other.

強磁性記録層に隣接して、書き込み電流の通電により発熱して第二の強磁性膜を加熱する加熱層を設けてもよい。 A heating layer for heating the second ferromagnetic film by generating heat by applying a write current may be provided adjacent to the ferromagnetic recording layer.

本発明のトンネル磁気抵抗効果素子は、電流を流すための電極と、トンネル磁気抵抗効果素子に流れる電流をオン・オフ制御するスイッチング素子とを設けて、強磁性記録層の磁化がスピントランスファートルクにより反転可能な磁気メモリセルを構成することができる。また、その磁気メモリセルを複数個アレイ状に配列し、複数の磁気メモリセルの中から所望の磁気メモリセルを選択する手段と、選択された磁気メモリセルに対して情報の読み出しあるいは書き込みを行う手段とを備えて、磁気ランダムアクセスメモリを構成することができる。 The tunnel magnetoresistive effect element of the present invention is provided with an electrode for flowing current and a switching element for controlling on / off of the current flowing through the tunnel magnetoresistive effect element so that the magnetization of the ferromagnetic recording layer is caused by spin transfer torque. A reversible magnetic memory cell can be constructed. In addition, a plurality of magnetic memory cells are arranged in an array, a means for selecting a desired magnetic memory cell from the plurality of magnetic memory cells, and information is read from or written to the selected magnetic memory cell. And a magnetic random access memory.

本発明によると、書き込み電流を増加させずに読み出しによる誤書き込みを低減可能なトンネル磁気抵抗効果素子が得られるので、トンネル磁気抵抗効果素子を微細化することが可能になり、不揮発性磁気メモリの大容量化に寄与する。 According to the present invention, it is possible to obtain a tunnel magnetoresistive element capable of reducing erroneous writing due to reading without increasing a write current. Therefore, the tunnel magnetoresistive element can be miniaturized, and the nonvolatile magnetic memory Contributes to large capacity.

スピントランスファートルク書き込み方式の不揮発性磁気メモリにおいて、読み出しにより誤書き込みが起こる確率Ｐは、Y. Higo el al., Applied Physics Letters 87, 082502 (2005)によると、
Ｐ＝１−exp{（ｔ／τ₀）exp[Ｅ／ｋＴ（１−Ｉ／Ｉ_c0）]}
と表される。ここで、ｔは読み出し電流Ｉを印加している時間、τ₀は１０^-9（ｓｅｃ）である。Ｅ／ｋＴは熱安定性の指標であり、強磁性記録層の磁化の大きさＭ、異方性磁界Ｈ_K、強磁性記録層の体積Ｖの積に比例している（Ｅ／ｋＴ∝ＭＨ_KＶ）。Ｉ_c0はゼロケルビンでの書き込み電流であり、ダンピング定数α、磁化の大きさの２乗、磁性記録層の体積に比例している（Ｉ_c0∝αＭ²Ｖ）。 According to Y. Higo el al., Applied Physics Letters 87, 082502 (2005), the probability P of erroneous writing by reading in the non-volatile magnetic memory of the spin transfer torque writing system is as follows:
P = 1−exp {(t / τ ₀ ) exp [E / kT (1−I / I _c0 )]}
It is expressed. Here, t is the time during which the read current I is applied, and τ ₀ is 10 ⁻⁹ (sec). E / kT is an index of thermal stability and is proportional to the product of the magnitude M of the magnetization of the ferromagnetic recording layer, the anisotropic magnetic field H _K , and the volume V of the ferromagnetic recording layer (E / kT∝MH). _KV ). I _c0 is a write current in zero Kelvin, and is proportional to the damping constant α, the square of the magnitude of magnetization, and the volume of the magnetic recording layer (I _c0 ∝αM ² V).

書き込み動作時に加熱を利用して低書き込み電流を実現する従来のトンネル磁気抵抗効果素子（図１参照）は、絶縁層１０１を挟んで設けられた強磁性固定層１００と、強磁性記録層１０２で構成される。強磁性固定層１００は、その磁化方向が固定されている。強磁性記録層１０２は、加熱により磁化の大きさが減少するという特徴を有する。読み出し動作時（図１（ａ））には、強磁性記録層１０２の磁化が大きく、書き込みに必要な電流も大きいため書き込みが困難である。書き込み動作時（図１（ｂ））には、加熱することにより記録層１０２の磁化を減少させて書き込み電流を低減する。 A conventional tunnel magnetoresistive element (see FIG. 1) that realizes a low write current by using heating during a write operation includes a ferromagnetic pinned layer 100 and a ferromagnetic recording layer 102 provided with an insulating layer 101 interposed therebetween. Composed. The magnetization direction of the ferromagnetic fixed layer 100 is fixed. The ferromagnetic recording layer 102 has a feature that the magnitude of magnetization is reduced by heating. During the reading operation (FIG. 1A), the magnetization of the ferromagnetic recording layer 102 is large and the current required for writing is large, so that writing is difficult. During the write operation (FIG. 1B), the magnetization of the recording layer 102 is reduced by heating to reduce the write current.

本発明では、強磁性記録層に、非磁性導電膜を介してフェリ磁性体を交換結合させることにより、読み出し動作時と書き込み動作時で強磁性記録層のダンピング定数を変化させる。ここで、本明細書における「フェリ磁性体」とは、Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｄｙなどの希土類遷移金属（ＲＥ）とＦｅ，Ｃｏ，Ｎｉなどの遷移金属（ＴＭ）の合金からなるフェリ磁性体と、ＲＥとＴＭを複数層積層させた積層構造のフェリ磁性体、ＴＭ及びＴＭからなる合金と前記合金からなるフェリ磁性体を複数層積層させた積層構造のフェリ磁性体を含む用語とする。読み出し動作時において、強磁性記録層のダンピング定数は従来構造（図１）に比べて増加するのでＩ_c0は増加する。また、読み出し動作時に強磁性記録層の異方性磁界も増加させることが可能なのでＥ／ｋＴが増加し、従来構造（図１）に比べて誤書込みを低減可能である。書込み動作時には、強磁性記録層のダンピング定数と磁化を低減できるため、書き込み電流は増加しない。 In the present invention, the damping constant of the ferromagnetic recording layer is changed between the read operation and the write operation by exchange coupling the ferrimagnetic material to the ferromagnetic recording layer via a nonmagnetic conductive film. Here, the “ferrimagnetic material” in this specification is an alloy of a rare earth transition metal (RE) such as Nd, Sm, Eu, Gd, Tb, or Dy and a transition metal (TM) such as Fe, Co, or Ni. A ferrimagnetic body having a laminated structure in which a plurality of layers of RE and TM are laminated, and a ferrimagnetic body having a laminated structure in which a plurality of ferrimagnetic bodies made of an alloy of TM and TM and the alloy are laminated. It is a term. During the read operation, the damping constant of the ferromagnetic recording layer increases as compared with the conventional structure (FIG. 1), so that I _c0 increases. Further, since the anisotropic magnetic field of the ferromagnetic recording layer can be increased during the read operation, E / kT is increased, and erroneous writing can be reduced as compared with the conventional structure (FIG. 1). During the write operation, the damping constant and magnetization of the ferromagnetic recording layer can be reduced, so that the write current does not increase.

本発明のトンネル磁気抵抗効果素子では、非磁性導電層を挟んで設けられた第一の強磁性膜と第二の強磁性膜を強磁性記録層に適用する。ここで、第二の強磁性膜はフェリ磁性体とし、そのフェリ磁性体の角運動量補償温度は読み出し動作温度近傍に設計する。また、第一の強磁性膜と第二の強磁性膜の磁化方向は前記非磁性導電層を介して交換結合しており、前記角運動量補償温度より高温において、それぞれ磁化方向がほぼ逆方向になるようにする。 In the tunnel magnetoresistive effect element of the present invention, the first ferromagnetic film and the second ferromagnetic film provided with the nonmagnetic conductive layer interposed therebetween are applied to the ferromagnetic recording layer. Here, the second ferromagnetic film is a ferrimagnetic material, and the angular momentum compensation temperature of the ferrimagnetic material is designed in the vicinity of the reading operation temperature. In addition, the magnetization directions of the first ferromagnetic film and the second ferromagnetic film are exchange-coupled via the nonmagnetic conductive layer, and the magnetization directions are substantially opposite to each other at a temperature higher than the angular momentum compensation temperature. To be.

フェリ磁性体のダンピング定数の温度変化は、角運動量補償温度近傍において極大値をとる。第一の強磁性層と第二の強磁性層の磁化は交換結合しているため、読み出し動作温度において、強磁性記録層全体のダンピング定数も増加する。また、角運動量補償温度は磁化補償温度近傍にあるため、保磁力も極大値近傍にある。そのため、第二の強磁性層の保磁力の増大に伴い、第一の強磁性層に異方性磁界が付与される。その結果、読み出し動作時においてＩ_c0とＥ／ｋＴが増加するので、誤書き込みを低減することが可能である。 The temperature change of the damping constant of the ferrimagnetic material has a maximum value near the angular momentum compensation temperature. Since the magnetizations of the first ferromagnetic layer and the second ferromagnetic layer are exchange coupled, the damping constant of the entire ferromagnetic recording layer also increases at the read operation temperature. Further, since the angular momentum compensation temperature is in the vicinity of the magnetization compensation temperature, the coercive force is also in the vicinity of the maximum value. Therefore, as the coercive force of the second ferromagnetic layer increases, an anisotropic magnetic field is applied to the first ferromagnetic layer. As a result, since I _c0 and E / kT increase during the read operation, erroneous writing can be reduced.

書き込みの際には、トンネル磁気抵抗効果素子に流す書き込み電流によって、又は加熱機構を用いてフェリ磁性体を角運動量補償温度以上の温度まで加熱する。磁化補償温度より高温において、フェリ磁性体のダンピング定数は読み出し動作温度の場合よりも減少する。また、フェリ磁性体は第一の強磁性層の磁化と逆方向の磁化を示し、かつ読み出し動作温度の場合よりも磁化が増加するため強磁性記録層全体の磁化は減少する。その結果、本発明を用いない場合と比較して書き込み電流を低減可能である。 At the time of writing, the ferrimagnetic material is heated to a temperature equal to or higher than the angular momentum compensation temperature by a writing current passed through the tunnel magnetoresistive element or by using a heating mechanism. At a temperature higher than the magnetization compensation temperature, the damping constant of the ferrimagnetic material is smaller than that at the read operation temperature. In addition, the ferrimagnetic material exhibits a magnetization in the direction opposite to the magnetization of the first ferromagnetic layer, and the magnetization increases as compared with the case of the reading operation temperature, so that the magnetization of the entire ferromagnetic recording layer decreases. As a result, the write current can be reduced as compared with the case where the present invention is not used.

本発明の構造を用いずに強磁性記録層をフェリ磁性体だけで構成した場合、角運動量補償温度を読み出し動作温度近傍に設計すると、読み出し動作時においてスイッチング磁界は増加するため、磁界書き込み方式では誤書込みを低減可能である。しかし本発明で適用するスピントランスファートルクによる書き込み方式では、強磁性記録層の磁化が小さくなるため、Ｉ_c0が低下し誤書込みが増加してしまう可能性がある。 When the ferromagnetic recording layer is composed only of a ferrimagnetic material without using the structure of the present invention, if the angular momentum compensation temperature is designed near the read operation temperature, the switching magnetic field increases during the read operation. Erroneous writing can be reduced. However, in the writing method using the spin transfer torque applied in the present invention, since the magnetization of the ferromagnetic recording layer is reduced, there is a possibility that I _c0 is lowered and erroneous writing is increased.

［実施例１］
図２は、本発明の磁気メモリセルに用いるトンネル磁気抵抗効果素子の一例の断面模式図である。このトンネル磁気抵抗効果素子２００は、配向制御膜２０１、反強磁性膜２０２、強磁性固定層２０３、絶縁膜２０４、強磁性記録層２０５を備え、適当な温度で熱処理することにより磁気抵抗比が最適化される。強磁性記録層２０５は第一の強磁性膜２０６、第一の非磁性導電膜２０７、第二の強磁性膜２０８で構成されている。強磁性固定層２０３は、第四の磁性膜２０９、第二の非磁性導電膜２１０、第三の強磁性膜２１１で構成される。なお、図３のように強磁性固定層２０３が単層であるトンネル磁気抵抗効果素子３００も用いることができる。 [Example 1]
FIG. 2 is a schematic cross-sectional view of an example of a tunnel magnetoresistive element used in the magnetic memory cell of the present invention. The tunnel magnetoresistive effect element 200 includes an orientation control film 201, an antiferromagnetic film 202, a ferromagnetic fixed layer 203, an insulating film 204, and a ferromagnetic recording layer 205, and has a magnetoresistance ratio by heat treatment at an appropriate temperature. Optimized. The ferromagnetic recording layer 205 includes a first ferromagnetic film 206, a first nonmagnetic conductive film 207, and a second ferromagnetic film 208. The ferromagnetic pinned layer 203 includes a fourth magnetic film 209, a second nonmagnetic conductive film 210, and a third ferromagnetic film 211. Note that, as shown in FIG. 3, a tunnel magnetoresistive element 300 in which the ferromagnetic fixed layer 203 is a single layer can also be used.

配向制御膜２０１は、例えばＮｉＦｅやＴａとＮｉＦｅの積層膜などであり、反強磁性膜２０２の配向性を向上させ、安定した反強磁性結合を実現することができれば他の材料を用いてもよい。反強磁性膜２０２は膜厚８ｎｍのＭｎＩｒが望ましい。ＭｎＰｔ，ＭｎＦｅを用いることもできる。膜厚は反強磁性を示すために十分な膜厚以上の膜厚が望ましい。第四の強磁性膜２０９にはＣｏＦｅ、第二の非磁性導電膜２１０にはＲｕ、第三の強磁性膜２１１には体心立方構造のＣｏＦｅＢが望ましい。第四の強磁性膜２０９、第二の非磁性導電膜２１０、第三の強磁性膜２１１は、第四の強磁性膜２０９と第三の強磁性膜２１１の磁化が反強磁性結合し、かつ第四の強磁性膜２０９と第三の強磁性膜２１１の磁化の大きさがほぼ等しくなるように材料と膜厚を選択する。図３のように強磁性固定層２０３が単層で構成される場合、強磁性固定層２０３はＣｏＦｅＢであることが望ましい。絶縁膜２０４は、岩塩構造をもつ酸化マグネシウム結晶膜であり、（１００）方向に配向した膜が望ましい。膜厚は０．８〜１．５ｎｍが望ましい。 The orientation control film 201 is, for example, NiFe or a stacked film of Ta and NiFe, and other materials can be used as long as the orientation of the antiferromagnetic film 202 can be improved and stable antiferromagnetic coupling can be realized. Good. The antiferromagnetic film 202 is preferably 8 nm thick MnIr. MnPt and MnFe can also be used. The film thickness is desirably a film thickness larger than a sufficient film thickness to exhibit antiferromagnetism. The fourth ferromagnetic film 209 is preferably CoFe, the second nonmagnetic conductive film 210 is Ru, and the third ferromagnetic film 211 is CoFeB having a body-centered cubic structure. The fourth ferromagnetic film 209, the second nonmagnetic conductive film 210, and the third ferromagnetic film 211 have antiferromagnetic coupling between the magnetizations of the fourth ferromagnetic film 209 and the third ferromagnetic film 211, In addition, the material and film thickness are selected so that the magnitudes of magnetization of the fourth ferromagnetic film 209 and the third ferromagnetic film 211 are substantially equal. When the ferromagnetic pinned layer 203 is composed of a single layer as shown in FIG. 3, the ferromagnetic pinned layer 203 is preferably CoFeB. The insulating film 204 is a magnesium oxide crystal film having a rock salt structure, and a film oriented in the (100) direction is desirable. The film thickness is desirably 0.8 to 1.5 nm.

以下に第一の強磁性膜２０６が強磁性体、第二の強磁性膜２０８がフェリ磁性体で構成される場合について述べる。第一の強磁性膜２０６は体心立方格子構造のＣｏＦｅＢが望ましい。第二の強磁性膜２０８はＧｄＣｏ，ＧｄＦｅＣｏ，ＴｂＦｅＣｏなど、Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｄｙなどの希土類遷移金属（ＲＥ）とＦｅ，Ｃｏ，Ｎｉなどの遷移金属（ＴＭ）の合金からなるフェリ磁性体であり、膜厚は２ｎｍ以上が望ましい。第一の強磁性膜２０６（第二の強磁性膜２０８）の磁化と膜厚をそれぞれＭ１，Ｔ１（Ｍ２，Ｔ２）とすると、書き込み動作時において、Ｍ１×Ｔ１＝Ｍ２×Ｔ２となるように第一の強磁性膜２０６と第二の強磁性膜２０８の膜厚を調整すると、書き込み電流の低減の効果が大きい。しかし、書き込みの際に強磁性記録層２０５の磁化を低減し、書き込み電流を許容範囲内にできれば、必ずしも上式の関係を満たさなくとも良い。フェリ磁性体の角運動量補償温度は読み出し動作温度近傍に設計する。ここで読み出し動作温度近傍は、トンネル磁気抵抗効果素子２００の抵抗値を検出する温度±３０℃以内が望ましい。角運動量補償温度は磁化補償温度に近傍にあるので、磁化補償温度を調整すれば角運動量補償温度も調整可能である。磁化補償温度の調整は、フェリ磁性体のＲＥとＴＭの組成を調整することで実現可能である。例えば、ＧｄＣｏを用いた場合には、Ｃｏの組成が７０〜８０％で室温付近に磁化補償温度をもつ。 The case where the first ferromagnetic film 206 is made of a ferromagnetic material and the second ferromagnetic film 208 is made of a ferrimagnetic material will be described below. The first ferromagnetic film 206 is preferably CoFeB having a body-centered cubic lattice structure. The second ferromagnetic film 208 is made of an alloy of a rare earth transition metal (RE) such as Nd, Sm, Eu, Gd, Tb, or Dy and a transition metal (TM) such as Fe, Co, or Ni, such as GdCo, GdFeCo, or TbFeCo. The film thickness is desirably 2 nm or more. When the magnetization and film thickness of the first ferromagnetic film 206 (second ferromagnetic film 208) are M1 and T1 (M2, T2), respectively, M1 × T1 = M2 × T2 during the write operation. When the film thicknesses of the first ferromagnetic film 206 and the second ferromagnetic film 208 are adjusted, the effect of reducing the write current is great. However, if the magnetization of the ferromagnetic recording layer 205 is reduced at the time of writing and the write current can be within an allowable range, the relationship of the above formula does not necessarily have to be satisfied. The angular momentum compensation temperature of the ferrimagnetic material is designed near the reading operation temperature. Here, the temperature near the reading operation temperature is desirably within a temperature of ± 30 ° C. for detecting the resistance value of the tunnel magnetoresistive element 200. Since the angular momentum compensation temperature is close to the magnetization compensation temperature, the angular momentum compensation temperature can be adjusted by adjusting the magnetization compensation temperature. Adjustment of the magnetization compensation temperature can be realized by adjusting the composition of RE and TM of the ferrimagnetic material. For example, when GdCo is used, the composition of Co is 70 to 80% and the magnetization compensation temperature is around room temperature.

第一の非磁性導電膜２０７はＲｕなどからなる。第一の強磁性膜２０６と第二の強磁性膜２０８の磁化方向は第一の非磁性導電膜２０７を介して交換結合しており、角運動量補償温度より高温においてそれぞれの磁化方向がほぼ反平行になるように非磁性導電膜２０７の材料と膜厚を調整する。 The first nonmagnetic conductive film 207 is made of Ru or the like. The magnetization directions of the first ferromagnetic film 206 and the second ferromagnetic film 208 are exchange-coupled via the first nonmagnetic conductive film 207, and the magnetization directions of the first ferromagnetic film 206 and the second ferromagnetic film 208 are substantially opposite at temperatures higher than the angular momentum compensation temperature. The material and film thickness of the nonmagnetic conductive film 207 are adjusted so as to be parallel.

次に、本発明で適用するフェリ磁性体の特徴について述べる。前記フェリ磁性体中ではＲＥとＴＭの磁化方向はほほ逆方向を向いており、フェリ磁性体全体としてＲＥとＴＭの差分の磁化が現れる。図４（ａ）に、フェリ磁性体の磁化の温度依存性の模式図を示す。ＲＥとＴＭのそれぞれの磁化の大きさと温度依存性は異なっており、一般にＲＥの方がＴＭよりも強磁性転移温度が低く、低温でＲＥの方がＴＭよりも磁化の大きさが大きい。ここで、強磁性転移温度とは強磁性秩序を示す臨界の温度であり、これよりも高温で強磁性体は強磁性を示さなくなる。磁化補償温度より低温では、ＲＥの磁化の方がＴＭよりも大きいため、フェリ磁性体全体の磁化は主にＲＥの磁化方向を反映する（図４（ｄ）参照）。温度が上昇し磁化補償温度になると、ＴＭよりもＲＥの方が磁化の減少量は大きいため、ＲＥとＴＭの磁化の大きさが釣り合い、フェリ磁性体全体の磁化はゼロとなる（図４（ｅ）参照）。また、磁化補償温度より高温ではＴＭの磁化の方がＲＥよりも大きくなる（図４（ｆ）参照）。したがって、第一の非磁性導電膜２０７を介して第一の強磁性膜２０６とフェリ磁性体である第二の強磁性膜２０８中のＴＭの磁化方向が反平行に結合するように設計すれば、磁化補償温度より高温において、第一の強磁性層と第二の強磁性膜２０８の磁化はほぼ反対方向となる。 Next, features of the ferrimagnetic material applied in the present invention will be described. In the ferrimagnetic material, the magnetization directions of RE and TM are almost opposite to each other, and the difference between RE and TM appears in the entire ferrimagnetic material. FIG. 4A shows a schematic diagram of the temperature dependence of the magnetization of the ferrimagnetic material. The magnitudes of magnetization and temperature dependence of RE and TM are different. Generally, RE has a lower ferromagnetic transition temperature than TM, and RE has a larger magnitude of magnetization than TM at a low temperature. Here, the ferromagnetic transition temperature is a critical temperature exhibiting a ferromagnetic order, and the ferromagnetic material does not exhibit ferromagnetism at a temperature higher than this. At a temperature lower than the magnetization compensation temperature, the magnetization of RE is larger than TM, so the magnetization of the entire ferrimagnetic material mainly reflects the magnetization direction of RE (see FIG. 4D). When the temperature rises to the magnetization compensation temperature, the amount of decrease in magnetization is larger in RE than in TM, so the magnitude of magnetization in RE and TM is balanced, and the magnetization of the entire ferrimagnetic material becomes zero (FIG. 4 ( e)). Further, at a temperature higher than the magnetization compensation temperature, the magnetization of TM becomes larger than that of RE (see FIG. 4F). Therefore, if the first ferromagnetic film 206 and the second ferromagnetic film 208, which is a ferrimagnetic material, are designed to be coupled antiparallel to each other via the first nonmagnetic conductive film 207. At a temperature higher than the magnetization compensation temperature, the magnetizations of the first ferromagnetic layer and the second ferromagnetic film 208 are substantially opposite to each other.

以上では、フェリ磁性体の磁化の温度依存性について述べたが、フェリ磁性体にはダンピング定数、保磁力の温度依存性にも特徴がある。ここで、ダンピング定数は磁化の運動に対する摩擦に関係した定数であり、保磁力は磁化方向を反転するために必要な磁場の大きさである。図４（ｂ）はフェリ磁性体のダンピング定数の温度依存性の模式図、図４（ｃ）は保磁力の温度依存性の模式図である。ダンピング定数は角運動量補償温度において極大値をとる。ここで角運動量補償温度は、フェリ磁性体全体でＲＥとＴＭの示す全角運動量がゼロとなる温度である。また、保磁力は磁化補償温度において極大値をとる。ＲＥ及びＴＭの示す磁化はそれぞれのもつ全角運動量に比例するが、それぞれの比例係数が異なるため、ＲＥとＴＭの合金からなるフェリ磁性体ではフェリ磁性体全体の磁化がゼロとなる磁化補償温度と角運動量補償温度は必ずしも一致するとは限らない。しかし角運動量補償温度は磁化補償温度の近傍になり、例えばＣｏＧｄ（Ｃｏ組成〜７８％）では角運動量補償温度が磁化補償温度よりも３０℃程度高くなる。図４（ａ）−（ｃ）は角運動量補償温度が磁化補償温度よりも高い場合の模式図であるが、角運動量補償温度は磁化補償温度よりも低くても良い。 Although the temperature dependence of the magnetization of the ferrimagnetic material has been described above, the ferrimagnetic material is also characterized by the temperature dependence of the damping constant and the coercive force. Here, the damping constant is a constant related to the friction with respect to the motion of magnetization, and the coercive force is the magnitude of the magnetic field necessary to reverse the magnetization direction. FIG. 4B is a schematic diagram of the temperature dependence of the damping constant of the ferrimagnetic material, and FIG. 4C is a schematic diagram of the temperature dependence of the coercive force. The damping constant takes a maximum value at the angular momentum compensation temperature. Here, the angular momentum compensation temperature is a temperature at which the total angular momentum indicated by RE and TM becomes zero in the entire ferrimagnetic material. Further, the coercive force takes a maximum value at the magnetization compensation temperature. Magnetization indicated by RE and TM is proportional to the total angular momentum of each, but since the proportional coefficients of each are different, in the ferrimagnetic material made of an alloy of RE and TM, the magnetization compensation temperature at which the magnetization of the entire ferrimagnetic material becomes zero Angular momentum compensation temperatures do not always match. However, the angular momentum compensation temperature is close to the magnetization compensation temperature. For example, in CoGd (Co composition to 78%), the angular momentum compensation temperature is about 30 ° C. higher than the magnetization compensation temperature. 4A to 4C are schematic views when the angular momentum compensation temperature is higher than the magnetization compensation temperature, but the angular momentum compensation temperature may be lower than the magnetization compensation temperature.

続いて、本発明のトンネル磁気抵抗効果素子の読み出し、書き込み動作について図５を用いて説明する。読み出しによる誤書込みは、読み出し動作時にゼロケルビンでの書き込み電流Ｉ_c0と熱安定性の指標Ｅ／ｋＴを増加させることにより低減可能である。ここで、Ｅ／ｋＴは磁化の大きさ、異方性磁界、体積に比例し、Ｉ_c0はダンピング定数、磁化の大きさの２乗、体積にほぼ比例している。 Next, read and write operations of the tunnel magnetoresistive effect element of the present invention will be described with reference to FIG. The erroneous writing due to reading can be reduced by increasing the writing current I _c0 at zero Kelvin and the thermal stability index E / kT during the reading operation. Here, E / kT is proportional to the magnitude of magnetization, anisotropic magnetic field, and volume, and I _c0 is substantially proportional to the damping constant, the square of magnitude of magnetization, and the volume.

図５（ａ）に、読み出し動作時における強磁性記録層５００の磁化配列を示す。読み出し動作時の温度は角運動量補償温度及び磁化補償温度近傍にあるため、フェリ磁性体の磁化の大きさはゼロに近い。この状態では、フェリ磁性体の内部でＲＥとＴＭの示す磁化の大きさがほぼ同じでほぼ逆方向に結合している。そのため、フェリ磁性体中で磁化及びスピンが熱的に不安定な状態にあるわけではない。また、第一の強磁性膜５０１と第二の強磁性膜５０３の間の交換結合は、非磁性導電膜を介した両界面のスピン同士の結合である。そのため、第一の強磁性膜の磁化方向も熱的に不安定になることはない。読み出し動作時の温度は角運動量補償温度近傍にあるため、第二の強磁性膜５０３のダンピング定数は極大値近傍にある。第一の強磁性膜５０１と第二の強磁性膜５０３の磁化は、第一の非磁性導電膜５０２を介して互いにほぼ逆方向となるように交換結合しているので、強磁性記録層５００全体のダンピング定数も増加する。そのため、本発明を用いない場合と比較してＩ_c0を増加させることが可能である。また第二の強磁性膜５０３の保磁力は磁化補償温度において極大値をとり、角運動量補償温度は磁化補償温度近傍にあるため、読み出し動作時において第二の強磁性膜５０３の保磁力も大きい。したがって、第二の強磁性膜から第一の強磁性膜に異方性磁界が付与され、本発明を用いない場合と比較して読み出しの際にＥ／ｋＴを増加させることが可能である。以上から、読み出し動作時の誤書込みを低減可能である。 FIG. 5A shows the magnetization arrangement of the ferromagnetic recording layer 500 during the read operation. Since the temperature during the read operation is in the vicinity of the angular momentum compensation temperature and the magnetization compensation temperature, the magnitude of magnetization of the ferrimagnetic material is close to zero. In this state, the magnitudes of the magnetizations indicated by RE and TM are substantially the same in the ferrimagnetic material, and are coupled in substantially opposite directions. Therefore, magnetization and spin are not in a thermally unstable state in the ferrimagnetic material. Further, the exchange coupling between the first ferromagnetic film 501 and the second ferromagnetic film 503 is a coupling between spins at both interfaces via the nonmagnetic conductive film. Therefore, the magnetization direction of the first ferromagnetic film does not become thermally unstable. Since the temperature during the reading operation is in the vicinity of the angular momentum compensation temperature, the damping constant of the second ferromagnetic film 503 is in the vicinity of the maximum value. Since the magnetizations of the first ferromagnetic film 501 and the second ferromagnetic film 503 are exchange-coupled through the first nonmagnetic conductive film 502 so as to be in opposite directions to each other, the ferromagnetic recording layer 500 The overall damping constant also increases. Therefore, I _c0 can be increased as compared with the case where the present invention is not used. The coercive force of the second ferromagnetic film 503 has a maximum value at the magnetization compensation temperature, and the angular momentum compensation temperature is in the vicinity of the magnetization compensation temperature. . Therefore, an anisotropic magnetic field is applied from the second ferromagnetic film to the first ferromagnetic film, and it is possible to increase E / kT at the time of reading as compared with the case where the present invention is not used. From the above, erroneous writing during the read operation can be reduced.

次に、書き込み動作を図５（ｂ）の書き込み動作時における強磁性記録層５００の磁化配列を用いて説明する。書き込み動作時には、トンネル磁気抵抗効果素子に流した書き込み電流を用いて第二の強磁性膜５０３を角運動量補償温度より高い温度にする。例えば、素子サイズ１００×２００ｎｍ²、強磁性記録層の膜厚５ｎｍ、抵抗１ｋΩの素子に１００μＡ、パルス幅１０ｎｓの書き込み電流を流した場合を考える。書き込み電流が発生するジュール熱は主に高抵抗の絶縁膜２０４で発生する。発生したジュール熱のすべてが強磁性記録層で消費されるとすると、２５０℃加熱することが可能である。ここで強磁性記録層の比熱を４×１０⁶Ｊ／ｍ³Ｋと仮定した。書き込み電流の場合と同様にして読み出し電流による発熱を見積もると、読み出し電流が２０μＡ、パルス幅１０ｎｓとした場合、強磁性記録層は１０℃温度上昇する。この読み出し電流による発熱は、角運動量補償温度の設計マージン内にあるため、読み出し動作上問題にならない。 Next, the write operation will be described using the magnetization arrangement of the ferromagnetic recording layer 500 in the write operation of FIG. During the write operation, the second ferromagnetic film 503 is set to a temperature higher than the angular momentum compensation temperature by using a write current passed through the tunnel magnetoresistive effect element. For example, consider a case where a write current of 100 μA and a pulse width of 10 ns is applied to an element having an element size of 100 × 200 nm ² , a ferromagnetic recording layer thickness of 5 nm, and a resistance of 1 kΩ. Joule heat generated by the write current is mainly generated in the high resistance insulating film 204. If all of the generated Joule heat is consumed in the ferromagnetic recording layer, heating at 250 ° C. is possible. Here, the specific heat of the ferromagnetic recording layer was assumed to be 4 × 10 ⁶ J / m ³ K. When the heat generation due to the read current is estimated in the same manner as in the case of the write current, the temperature of the ferromagnetic recording layer rises by 10 ° C. when the read current is 20 μA and the pulse width is 10 ns. The heat generated by the read current is within the design margin of the angular momentum compensation temperature, and therefore does not cause a problem in the read operation.

強磁性記録層の加熱温度は、トンネル磁気抵抗効果素子に接続された電極のサイズと膜厚、素子サイズ、強磁性記録層の膜厚、書き込み時間を調整することにより、所望の値に調節することが可能である。強磁性記録層の磁化反転に必要な電流と加熱に必要な電流の大きさ及びパルス幅が異なる場合には、図６のように、トンネル磁気抵抗効果素子６００に加熱電流６０１を流して所望の温度にまで加熱した後に、書き込み電流６０２を流して書き込みを行うこともできる。 The heating temperature of the ferromagnetic recording layer is adjusted to a desired value by adjusting the size and thickness of the electrode connected to the tunnel magnetoresistive effect element, the element size, the thickness of the ferromagnetic recording layer, and the writing time. It is possible. When the current necessary for reversing the magnetization of the ferromagnetic recording layer differs from the current necessary for heating and the pulse width, as shown in FIG. 6, a heating current 601 is passed through the tunnel magnetoresistive element 600 to obtain a desired current. Writing can also be performed by supplying a writing current 602 after heating to a temperature.

第二の強磁性膜５０３の温度が角運動量補償温度より高温になると、ダンピング定数は読み出し動作時に比べて減少する。書き込み時のダンピング定数は、読み出し時の０．８以下となるまで加熱することが望ましい。また、第一の強磁性膜と第二の強磁性膜の磁化方向は互いにほぼ反平行に結合しているため、強磁性記録層全体の磁化を減少させることが可能である。書き込み電流はＩ_c0に比例しており、Ｉ_c0はダンピング定数と磁化の２乗に比例しているので、本発明を用いない場合に比べて書き込み電流を低減可能である。 When the temperature of the second ferromagnetic film 503 is higher than the angular momentum compensation temperature, the damping constant decreases compared to the reading operation. It is desirable to heat until the damping constant at the time of writing becomes 0.8 or less at the time of reading. Further, since the magnetization directions of the first ferromagnetic film and the second ferromagnetic film are coupled almost antiparallel to each other, it is possible to reduce the magnetization of the entire ferromagnetic recording layer. The write current is proportional to I _c0, since I _c0 is proportional to the square of the magnetization damping constant, it is possible to reduce the write current as compared with the case without the present invention.

上記の効果を確認するため、Ｅ／ｋＴ＝６０、１０００個のトンネル磁気抵抗効果素子に読み出し電流を１０年間流し続けた時に反転してしまう（誤書込みが起こる）確率を、読み出し電流に対して計算すると、図７のようになる。本発明を用いない場合に、Ｉ_c0＝１００μＡとすると図７の破線のようになる。読み出し電流を２０μＡとすると、約３５％の素子で誤書込みが起きしまう。本発明で、読み出しの際にダンピング定数aが２倍になり、Ｉ_c0も２倍になった場合の計算結果を、図７の実線に示す。読み出し電流が２０μＡの場合、誤書込みの確率は約０．２％となる。図７の計算では簡単のため、Ｅ／ｋＴの増加はないものとしたが、Ｅ／ｋＴが増加すればさらに誤書込みを低減することが可能となる。 In order to confirm the above effect, E / kT = 60, and the probability that the read current is reversed when a read current continues to flow through 1000 tunnel magnetoresistive elements for 10 years is determined with respect to the read current. The calculation is as shown in FIG. In the case where the present invention is not used, if I _c0 = 100 μA, a broken line in FIG. 7 is obtained. If the read current is 20 μA, erroneous writing occurs in about 35% of the elements. In the present invention, the solid line in FIG. 7 shows the calculation results when the damping constant a is doubled and I _c0 is doubled at the time of reading. When the read current is 20 μA, the probability of erroneous writing is about 0.2%. For the sake of simplicity in the calculation of FIG. 7, it is assumed that E / kT does not increase. However, if E / kT increases, erroneous writing can be further reduced.

書き込みの際に、ダンピング定数が読み出しの際の１／２なったとすると、書き込み電流は本発明を用いない場合と同じなる。また、書き込みの際には強磁性記録層の磁化が減少する。例えば磁化が読み出しの際の０．７倍になったとすると、書き込み電流は磁化の２乗に比例するため、全体として書き込み電流は本発明を用いない場合の約１／２となる。したがって、本発明のトンネル磁気抵抗効果素子をメモリセルに適用することにより、書き込み電流を増加させることなく、読み出しの際にＩ_c0とＥ／ｋＴを増加し、誤書き込みを低減可能である。 When writing, if the damping constant is ½ that during reading, the write current is the same as when the present invention is not used. Further, the magnetization of the ferromagnetic recording layer decreases during writing. For example, if the magnetization is 0.7 times that at the time of reading, the write current is proportional to the square of the magnetization, so the write current as a whole is about ½ that when the present invention is not used. Therefore, by applying the tunnel magnetoresistive effect element of the present invention to a memory cell, it is possible to increase I _c0 and E / kT at the time of reading without increasing the write current, and to reduce erroneous writing.

［実施例２］
図８は、本発明によるトンネル磁気抵抗効果素子の他の構成例の断面模式図である。このトンネル磁気抵抗効果素子８００は、配向制御膜８０１、反強磁性膜８０２、強磁性固定層８０３、絶縁膜８０４、強磁性記録層８０５を備え、適当な温度で熱処理することにより磁気抵抗比が最適化される。強磁性記録層８０５は、第一の強磁性膜８０６、第一の非磁性導電膜８０７、第二の強磁性膜８０８で構成されている。強磁性固定層８０３は、第四の強磁性膜８０９、第二の非磁性導電膜８１０、第三の強磁性膜８１１で構成される。なお、強磁性固定層８０３は、図３のように単層の強磁性固定層としてもよい。 [Example 2]
FIG. 8 is a schematic cross-sectional view of another configuration example of the tunnel magnetoresistive effect element according to the present invention. The tunnel magnetoresistive effect element 800 includes an orientation control film 801, an antiferromagnetic film 802, a ferromagnetic fixed layer 803, an insulating film 804, and a ferromagnetic recording layer 805, and has a magnetoresistance ratio by heat treatment at an appropriate temperature. Optimized. The ferromagnetic recording layer 805 includes a first ferromagnetic film 806, a first nonmagnetic conductive film 807, and a second ferromagnetic film 808. The ferromagnetic pinned layer 803 includes a fourth ferromagnetic film 809, a second nonmagnetic conductive film 810, and a third ferromagnetic film 811. The ferromagnetic fixed layer 803 may be a single-layer ferromagnetic fixed layer as shown in FIG.

配向制御膜８０１は、例えばＮｉＦｅやＴａとＮｉＦｅの積層膜などであり、反強磁性膜８０２の配向性を向上させ、安定した反強磁性結合を実現することができれば他の材料を用いてもよい。反強磁性膜８０２は膜厚８ｎｍのＭｎＩｒが望ましい。ＭｎＰｔ，ＭｎＦｅを用いることもできる。膜厚は反強磁性を示すために十分な膜厚以上の膜厚が望ましい。第四の強磁性膜８０９にはＣｏＦｅ、第二の非磁性導電膜８１０にはＲｕ、第三の強磁性膜８１１には体心立方構造のＣｏＦｅＢが望ましい。第四の強磁性膜８０９、第二の非磁性導電膜８１０、第三の強磁性膜８１１は、第四の強磁性膜８０９と第三の強磁性膜８１１の磁化が反強磁性結合し、かつ第四の強磁性膜８０９と第三の強磁性膜８１１の磁化の大きさがほぼ等しくなるように材料と膜厚を選択する。図３のように強磁性固定層が単層で構成される場合、強磁性固定層はＣｏＦｅＢであることが望ましい。絶縁膜８０４は、岩塩構造をもつ酸化マグネシウム結晶膜であり、（１００）方向に配向した膜が望ましい。膜厚は０．８〜１．５ｎｍが望ましい。 The orientation control film 801 is, for example, NiFe or a stacked film of Ta and NiFe, and other materials can be used as long as the orientation of the antiferromagnetic film 802 can be improved and stable antiferromagnetic coupling can be realized. Good. The antiferromagnetic film 802 is preferably MnIr with a thickness of 8 nm. MnPt and MnFe can also be used. The film thickness is desirably a film thickness larger than a sufficient film thickness to exhibit antiferromagnetism. The fourth ferromagnetic film 809 is preferably CoFe, the second nonmagnetic conductive film 810 is Ru, and the third ferromagnetic film 811 is preferably body-centered cubic CoFeB. The fourth ferromagnetic film 809, the second nonmagnetic conductive film 810, and the third ferromagnetic film 811 have antiferromagnetic coupling between the magnetizations of the fourth ferromagnetic film 809 and the third ferromagnetic film 811. The material and film thickness are selected so that the magnitudes of magnetization of the fourth ferromagnetic film 809 and the third ferromagnetic film 811 are substantially equal. When the ferromagnetic pinned layer is composed of a single layer as shown in FIG. 3, the ferromagnetic pinned layer is preferably CoFeB. The insulating film 804 is a magnesium oxide crystal film having a rock salt structure, and a film oriented in the (100) direction is desirable. The film thickness is desirably 0.8 to 1.5 nm.

以下に、第一の強磁性膜８０６が強磁性体、第二の強磁性膜８０８がフェリ磁性体で構成される場合について述べる。第一の強磁性膜８０６は、体心立方格子構造のＣｏＦｅＢが望ましい。第二の強磁性膜８０８はＮｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｄｙなどの希土類遷移金属（ＲＥ）とＦｅ，Ｃｏ，Ｎｉなどの遷移金属（ＴＭ）及びＣｏＦｅ，ＮｉＦｅなどのＴＭの合金を交互に複数層積層した積層構造のフェリ磁性体、ＧｄＣｏ，ＧｄＦｅＣｏ，ＴｂＦｅＣｏなどＲＥとＴＭの合金からなるフェリ磁性体と前記ＴＭ及びＣｏＦｅ，ＮｉＦｅなどの前記ＴＭの合金を交互に複数層積層させた積層構造のフェリ磁性体であり、例えばＴｂとＣｏの積層構造、ＧｄとＮｉＦｅの積層構造及びＣｏとＧｄＣｏ積層構造である。 The case where the first ferromagnetic film 806 is made of a ferromagnetic material and the second ferromagnetic film 808 is made of a ferrimagnetic material will be described below. The first ferromagnetic film 806 is preferably CoFeB having a body-centered cubic lattice structure. The second ferromagnetic film 808 is made of a rare earth transition metal (RE) such as Nd, Sm, Eu, Gd, Tb, or Dy, a transition metal (TM) such as Fe, Co, or Ni, and a TM alloy such as CoFe or NiFe. Multi-layered ferrimagnetic materials, such as GdCo, GdFeCo, TbFeCo and other ferrimagnetic materials made of alloys of RE and TM, and the above-mentioned TM and alloys of TM such as CoFe and NiFe were alternately laminated. A ferrimagnetic material having a laminated structure, for example, a laminated structure of Tb and Co, a laminated structure of Gd and NiFe, and a laminated structure of Co and GdCo.

第一の強磁性膜８０６（第二の強磁性膜８０８）の磁化と膜厚をそれぞれＭ１，Ｔ１（Ｍ２，Ｔ２）とすると、書き込み動作時において、Ｍ１×Ｔ１＝Ｍ２×Ｔ２となるように第一の強磁性膜８０６と第二の強磁性膜８０８の膜厚を調整すると、書き込み電流の低減の効果が大きい。しかし、書き込みの際に強磁性記録層８０５の磁化を低減し、書き込み電流を許容範囲内にできれば、必ずしも上式の関係を満たさなくとも良い。フェリ磁性体の角運動量補償温度は読み出し動作温度近傍に設計する。ここで読み出し動作温度近傍は、トンネル磁気抵抗効果素子８００の抵抗値を検出する温度±３０℃以内が望ましい。角運動量補償温度は磁化補償温度に近傍にあるので、磁化補償温度を調整すれば角運動量補償温度も調整可能である。磁化補償温度の調整は、ＲＥとＴＭの合金からなるフェリ磁性体におけるＲＥとＴＭの組成、又は前記積層構造のフェリ磁性のそれぞれの膜厚を調整することにより調整することができる。 Assuming that the magnetization and film thickness of the first ferromagnetic film 806 (second ferromagnetic film 808) are M1 and T1 (M2, T2), respectively, M1 × T1 = M2 × T2 during the write operation. When the film thicknesses of the first ferromagnetic film 806 and the second ferromagnetic film 808 are adjusted, the effect of reducing the write current is great. However, if the magnetization of the ferromagnetic recording layer 805 is reduced at the time of writing and the write current can be within an allowable range, the relationship of the above formula does not necessarily have to be satisfied. The angular momentum compensation temperature of the ferrimagnetic material is designed near the reading operation temperature. Here, the temperature near the reading operation temperature is desirably within a temperature of ± 30 ° C. for detecting the resistance value of the tunnel magnetoresistive element 800. Since the angular momentum compensation temperature is close to the magnetization compensation temperature, the angular momentum compensation temperature can be adjusted by adjusting the magnetization compensation temperature. The magnetization compensation temperature can be adjusted by adjusting the composition of RE and TM in the ferrimagnetic material made of an alloy of RE and TM, or the thickness of each of the ferrimagnetism of the laminated structure.

第一の非磁性導電膜８０７はＲｕなどである。第一の強磁性膜８０６と第二の強磁性膜８０８の磁化方向は第一の非磁性導電膜８０７を介して交換結合しており、角運動量補償温度より高温においてそれぞれの磁化方向がほぼ反平行になるように非磁性導電膜８０７の材料と膜厚を調整する。第二の強磁性膜８０８の前記ＴＭ及び前記ＴＭの合金で構成されている層が第一の非磁性導電膜８０７に接していると、交換結合の調整が比較的容易である。 The first nonmagnetic conductive film 807 is made of Ru or the like. The magnetization directions of the first ferromagnetic film 806 and the second ferromagnetic film 808 are exchange coupled through the first nonmagnetic conductive film 807, and the magnetization directions of the first ferromagnetic film 806 and the second ferromagnetic film 808 are substantially opposite at a temperature higher than the angular momentum compensation temperature. The material and film thickness of the nonmagnetic conductive film 807 are adjusted so as to be parallel. When the layer of the second ferromagnetic film 808 made of the TM and the alloy of TM is in contact with the first nonmagnetic conductive film 807, adjustment of exchange coupling is relatively easy.

本実施例のトンネル磁気抵抗効果素子の読み出し、書き込み動作は実施例１と同様であり、本発明のトンネル磁気抵抗効果素子をメモリセルに適用することにより、書き込み電流を増加させることなく、読み出しの際にＩ_c0とＥ／ｋＴを増加し、誤書き込みを低減可能である。 The read and write operations of the tunnel magnetoresistive effect element of this embodiment are the same as those of the first embodiment. By applying the tunnel magnetoresistive effect element of the present invention to the memory cell, the read operation can be performed without increasing the write current. In this case, I _c0 and E / kT can be increased to reduce erroneous writing.

［実施例３］
図９は、本発明によるトンネル磁気抵抗効果素子の他の構成例の断面模式図である。このトンネル磁気抵抗効果素子９００は、配向制御膜９０１、反強磁性膜９０２、強磁性固定層９０３、絶縁膜９０４、強磁性記録層９０５を備え、適当な温度で熱処理することにより磁気抵抗比が最適化される。強磁性記録層９０５は、第一の強磁性膜９０６、第一の非磁性導電膜９０７、第二の強磁性膜９０８で構成されている。強磁性固定層９０３は、第四の強磁性膜９０９、第二の非磁性導電膜９１０、第三の強磁性膜９１１で構成される。強磁性固定層９０３は、図３のように単層である構成も用いることができる。 [Example 3]
FIG. 9 is a schematic cross-sectional view of another configuration example of the tunnel magnetoresistive effect element according to the present invention. The tunnel magnetoresistive effect element 900 includes an orientation control film 901, an antiferromagnetic film 902, a ferromagnetic fixed layer 903, an insulating film 904, and a ferromagnetic recording layer 905, and has a magnetoresistance ratio by heat treatment at an appropriate temperature. Optimized. The ferromagnetic recording layer 905 includes a first ferromagnetic film 906, a first nonmagnetic conductive film 907, and a second ferromagnetic film 908. The ferromagnetic pinned layer 903 includes a fourth ferromagnetic film 909, a second nonmagnetic conductive film 910, and a third ferromagnetic film 911. The ferromagnetic pinned layer 903 can also have a single layer structure as shown in FIG.

配向制御膜９０１は、例えばＮｉＦｅやＴａとＮｉＦｅの積層膜などであり、反強磁性膜９０２の配向性を向上させ、安定した反強磁性結合を実現することができれば他の材料を用いてもよい。反強磁性膜９０２は膜厚８ｎｍのＭｎＩｒが望ましい。ＭｎＰｔ，ＭｎＦｅを用いることもできる。膜厚は反強磁性を示すために十分な膜厚以上の膜厚が望ましい。第四の強磁性膜９０９にはＣｏＦｅ、第二の非磁性導電膜９１０にはＲｕ、第三の強磁性膜９１１には体心立方構造のＣｏＦｅＢが望ましい。第四の強磁性膜９０９、第二の非磁性導電膜９１０、第三の強磁性膜９１１は、第四の強磁性膜９０９と第三の強磁性膜９１１の磁化が反強磁性結合し、かつ第四の強磁性膜９０９と第三の強磁性膜９１１の磁化の大きさがほぼ等しくなるように材料と膜厚を選択する。図３のように強磁性固定層が単層で構成される場合、強磁性固定層はＣｏＦｅＢであることが望ましい。絶縁膜９０４は、岩塩構造をもつ酸化マグネシウム結晶膜であり、（１００）方向に配向した膜が望ましい。膜厚は０．８〜１．５ｎｍが望ましい。 The orientation control film 901 is, for example, NiFe or a stacked film of Ta and NiFe, and other materials can be used as long as the orientation of the antiferromagnetic film 902 can be improved and stable antiferromagnetic coupling can be realized. Good. The antiferromagnetic film 902 is preferably MnIr with a thickness of 8 nm. MnPt and MnFe can also be used. The film thickness is desirably a film thickness larger than a sufficient film thickness to exhibit antiferromagnetism. The fourth ferromagnetic film 909 is preferably CoFe, the second nonmagnetic conductive film 910 is Ru, and the third ferromagnetic film 911 is CoFeB having a body-centered cubic structure. The fourth ferromagnetic film 909, the second nonmagnetic conductive film 910, and the third ferromagnetic film 911 have antiferromagnetic coupling between the magnetizations of the fourth ferromagnetic film 909 and the third ferromagnetic film 911, The material and film thickness are selected so that the magnitudes of magnetization of the fourth ferromagnetic film 909 and the third ferromagnetic film 911 are substantially equal. When the ferromagnetic pinned layer is composed of a single layer as shown in FIG. 3, the ferromagnetic pinned layer is preferably CoFeB. The insulating film 904 is a magnesium oxide crystal film having a rock salt structure, and a film oriented in the (100) direction is desirable. The film thickness is desirably 0.8 to 1.5 nm.

以下に、第一の強磁性膜９０６がフェリ磁性体、第二の強磁性膜９０８が強磁性体で構成される場合について述べる。第二の強磁性膜９０８はＣｏＦｅ，ＮｉＦｅなどが望ましい。第一の強磁性膜９０６は、Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｄｙなどの希土類遷移金属（ＲＥ）とＦｅ，Ｃｏ，Ｎｉなどの遷移金属（ＴＭ）及びＣｏＦｅ，ＮｉＦｅなどのＴＭの合金を交互に複数層積層した積層構造のフェリ磁性体、ＧｄＣｏ，ＧｄＦｅＣｏ，ＴｂＦｅＣｏなどＲＥとＴＭの合金からなるフェリ磁性体と前記ＴＭ及びＣｏＦｅ，ＮｉＦｅなどの前記ＴＭの合金を交互に複数層積層させた積層構造のフェリ磁性体であり、例えばＴｂとＣｏの積層構造、ＧｄとＮｉＦｅの積層構造及びＣｏとＧｄＣｏの積層構造である。絶縁膜９０４と第一の強磁性膜９０６の界面がＴＭ及びＴＭの合金で構成されていると磁気抵抗比の設計が比較的容易になるが十分な磁気抵抗比が得られれば、他の構成を用いることもできる。また、十分な磁気抵抗比が得られれば第一の強磁性層９０６として、上記ＲＥと上記ＴＭの合金からなるフェリ磁性体を用いることができる。 The case where the first ferromagnetic film 906 is made of a ferrimagnetic material and the second ferromagnetic film 908 is made of a ferromagnetic material will be described below. The second ferromagnetic film 908 is preferably CoFe, NiFe or the like. The first ferromagnetic film 906 is made of a rare earth transition metal (RE) such as Nd, Sm, Eu, Gd, Tb or Dy, a transition metal (TM) such as Fe, Co or Ni, or an alloy of TM such as CoFe or NiFe. Ferrimagnetic material having a laminated structure in which a plurality of layers are laminated alternately, a ferrimagnetic material composed of an alloy of RE and TM such as GdCo, GdFeCo, TbFeCo, and the like, and a plurality of such alloys of TM such as TM and CoFe, NiFe are laminated alternately. For example, a laminated structure of Tb and Co, a laminated structure of Gd and NiFe, and a laminated structure of Co and GdCo. If the interface between the insulating film 904 and the first ferromagnetic film 906 is made of TM and an alloy of TM, the design of the magnetoresistance ratio becomes relatively easy, but if a sufficient magnetoresistance ratio is obtained, other configurations are possible. Can also be used. If a sufficient magnetoresistance ratio is obtained, a ferrimagnetic material made of an alloy of RE and TM can be used as the first ferromagnetic layer 906.

第一の強磁性膜９０６（第二の強磁性膜９０８）の磁化と膜厚をそれぞれＭ１，Ｔ１（Ｍ２，Ｔ２）とすると、書き込み動作時において、Ｍ１×Ｔ１＝Ｍ２×Ｔ２となるように第一の強磁性膜９０６と第二の強磁性膜９０８の膜厚を調整すると、書き込み電流の低減の効果が大きい。しかし、書き込みの際に強磁性記録層９０５の磁化を低減し、書き込み電流を許容範囲内にできれば、必ずしも上式の関係を満たさなくとも良い。フェリ磁性体の角運動量補償温度は読み出し動作温度近傍に設計する。ここで読み出し動作温度近傍は、トンネル磁気抵抗効果素子９００の抵抗値を検出する温度±３０℃以内が望ましい。角運動量補償温度は磁化補償温度に近傍にあるので、磁化補償温度を調整すれば角運動量補償温度も調整可能である。磁化補償温度の調整は、ＲＥとＴＭの合金からなるフェリ磁性体におけるＲＥとＴＭの組成、又は積層構造のフェリ磁性のそれぞれの膜厚を調整することにより調整することができる。 When the magnetization and film thickness of the first ferromagnetic film 906 (second ferromagnetic film 908) are M1 and T1 (M2, T2), respectively, M1 × T1 = M2 × T2 at the time of writing operation. When the film thicknesses of the first ferromagnetic film 906 and the second ferromagnetic film 908 are adjusted, the effect of reducing the write current is great. However, if the magnetization of the ferromagnetic recording layer 905 is reduced during writing and the writing current can be within an allowable range, the relationship of the above formula does not necessarily have to be satisfied. The angular momentum compensation temperature of the ferrimagnetic material is designed near the reading operation temperature. Here, the temperature near the reading operation temperature is preferably within ± 30 ° C. for detecting the resistance value of the tunnel magnetoresistive element 900. Since the angular momentum compensation temperature is close to the magnetization compensation temperature, the angular momentum compensation temperature can be adjusted by adjusting the magnetization compensation temperature. The adjustment of the magnetization compensation temperature can be adjusted by adjusting the composition of RE and TM in the ferrimagnetic material made of an alloy of RE and TM, or the thickness of each of the ferrimagnetism of the laminated structure.

第一の非磁性導電膜９０７はＲｕなどである。第一の強磁性膜９０６と第二の強磁性膜９０８の磁化方向は第一の非磁性導電膜９０７を介して交換結合しており、角運動量補償温度より高温においてそれぞれの磁化方向がほぼ反平行になるように非磁性導電膜９０７の材料と膜厚を調整する。第一の非磁性導電膜９０７と第二の強磁性膜９０８の界面がＴＭ及びＴＭの合金で構成されている場合には、この調整が比較的容易である。 The first nonmagnetic conductive film 907 is made of Ru or the like. The magnetization directions of the first ferromagnetic film 906 and the second ferromagnetic film 908 are exchange-coupled via the first nonmagnetic conductive film 907, and the magnetization directions of the first ferromagnetic film 906 and the second ferromagnetic film 908 are substantially opposite to each other at a temperature higher than the angular momentum compensation temperature. The material and film thickness of the nonmagnetic conductive film 907 are adjusted so as to be parallel. This adjustment is relatively easy when the interface between the first nonmagnetic conductive film 907 and the second ferromagnetic film 908 is made of an alloy of TM and TM.

［実施例４］
図１０に、本発明によるトンネル磁気抵抗効果素子の他の構成例の断面図模式図を示す。このトンネル磁気抵抗効果素子１０００は、配向制御膜１００１、反強磁性膜１００２、強磁性固定層１００３、絶縁膜１００４、強磁性記録層１００５、加熱層１００９を備え、適当な温度で熱処理することにより磁気抵抗比が最適化される。強磁性記録層１００５は実施例１、実施例２の構成が望ましいが、加熱層で発生する熱が強磁性記録層を加熱するのに十分な場合には実施例３の構成を用いることもできる。強磁性固定層１００３は、第四の強磁性膜１００６、第二の非磁性導電膜１００７、第三の強磁性膜１００８で構成されている。強磁性固定層１００３は、図３のように単層である構成も用いることができる。 [Example 4]
FIG. 10 shows a schematic cross-sectional view of another configuration example of the tunnel magnetoresistive effect element according to the present invention. The tunnel magnetoresistive effect element 1000 includes an orientation control film 1001, an antiferromagnetic film 1002, a ferromagnetic fixed layer 1003, an insulating film 1004, a ferromagnetic recording layer 1005, and a heating layer 1009, and is heat-treated at an appropriate temperature. The magnetoresistance ratio is optimized. The configuration of Example 1 and Example 2 is desirable for the ferromagnetic recording layer 1005, but the configuration of Example 3 can also be used when the heat generated in the heating layer is sufficient to heat the ferromagnetic recording layer. . The ferromagnetic fixed layer 1003 includes a fourth ferromagnetic film 1006, a second nonmagnetic conductive film 1007, and a third ferromagnetic film 1008. The ferromagnetic pinned layer 1003 can be configured as a single layer as shown in FIG.

反強磁性膜１００２は膜厚８ｎｍのＭｎＩｒを用いることができる。ＭｎＰｔ，ＭｎＦｅを用いることもできる。また、膜厚は反強磁性を示すために十分な膜厚以上の膜厚が望ましい。第四の強磁性膜１００６にはＣｏＦｅ、第二の非磁性導電膜１００７にはＲｕ、第三の強磁性膜１００８には体心立方構造のＣｏＦｅＢが望ましい。第四の強磁性膜１００６、第二の非磁性導電膜１００７、第三の強磁性膜１００８は、第四の強磁性膜１００６と第三の強磁性膜１００８の磁化が反強磁性結合し、かつ第四の強磁性膜１００６と第三の強磁性膜１００８の磁化の大きさがほぼ等しくなるように材料と膜厚を選択する。絶縁膜１００４は、岩塩構造をもつ酸化マグネシウム結晶膜であり、（１００）方向に配向した膜が望ましい。膜厚は０．８〜１．５ｎｍを用いることができる。 As the antiferromagnetic film 1002, MnIr having a thickness of 8 nm can be used. MnPt and MnFe can also be used. Further, the film thickness is preferably greater than the film thickness sufficient to exhibit antiferromagnetism. The fourth ferromagnetic film 1006 is preferably CoFe, the second nonmagnetic conductive film 1007 is Ru, and the third ferromagnetic film 1008 is body-centered cubic CoFeB. The fourth ferromagnetic film 1006, the second nonmagnetic conductive film 1007, and the third ferromagnetic film 1008 have antiferromagnetic coupling between the magnetizations of the fourth ferromagnetic film 1006 and the third ferromagnetic film 1008, In addition, the material and the film thickness are selected so that the magnitudes of the magnetizations of the fourth ferromagnetic film 1006 and the third ferromagnetic film 1008 are substantially equal. The insulating film 1004 is a magnesium oxide crystal film having a rock salt structure, and a film oriented in the (100) direction is desirable. A film thickness of 0.8 to 1.5 nm can be used.

加熱層１００９は電流が流れると発熱し、強磁性記録層１００５中のフェリ磁性体で構成される膜を所望の温度にまで加熱するために十分な抵抗値を示す材料である。例えばタングステン、窒化チタン（ＴｉＮ）、窒化タンタル（ＴａＮ）、窒化タングステン（ＷＮ）、窒化チタンアルミ（ＴｉＡｌＮ）などの高融点金属が望ましい。実施例１、実施例２、実施例３の構造において、書き込み動作時にフェリ磁性体を所望の温度まで加熱することが困難な場合、本実施例は有効である。 The heating layer 1009 is a material that generates heat when a current flows and has a resistance value sufficient to heat the film made of the ferrimagnetic material in the ferromagnetic recording layer 1005 to a desired temperature. For example, refractory metals such as tungsten, titanium nitride (TiN), tantalum nitride (TaN), tungsten nitride (WN), and titanium nitride aluminum (TiAlN) are desirable. In the structures of Example 1, Example 2, and Example 3, this example is effective when it is difficult to heat the ferrimagnetic material to a desired temperature during a write operation.

読み出し方法は実施例１と同様である。書き込み動作時には、トンネル磁気抵抗効果素子に流した書き込み電流を用いて強磁性記録層１００５中のフェリ磁性体を角運動量補償温度より高い温度にする。強磁性記録層の磁化反転に必要な電流と加熱に必要な電流の大きさ及びパルス幅が異なる場合には、図６のように加熱電流６０１を流して所望の温度にまで加熱した後に書き込み電流６０２を流して書き込みを行うこともできる。 The reading method is the same as in the first embodiment. During the write operation, the ferrimagnetic material in the ferromagnetic recording layer 1005 is set to a temperature higher than the angular momentum compensation temperature by using a write current passed through the tunnel magnetoresistive element. In the case where the current required for reversing the magnetization of the ferromagnetic recording layer differs from the current required for heating and the pulse width, the heating current 601 is applied as shown in FIG. Writing can also be performed by flowing 602.

［実施例５］
図１１は、本発明のトンネル磁気抵抗効果素子を磁気メモリセルと磁気ランダムアクセスメモリに適用した場合の模式図である。磁気メモリセル１１００は、実施例１−４に記載のトンネル磁気抵抗効果素子１１０２、トンネル磁気抵抗効果素子１１０２に接続された電極１１０３、トンネル磁気抵抗効果素子１１０２に接続され、トンネル磁気抵抗効果素子１１０２に流れる電流のＯＮ／ＯＦＦを制御する選択トランジスタ１１０１、選択トランジスタ１１０１の電流のＯＮ／ＯＦＦを制御する信号を伝達するためのゲート電極１１０４で構成される。 [Example 5]
FIG. 11 is a schematic diagram when the tunnel magnetoresistive element of the present invention is applied to a magnetic memory cell and a magnetic random access memory. A magnetic memory cell 1100 includes a tunnel magnetoresistive effect element 1102 described in Example 1-4, an electrode 1103 connected to the tunnel magnetoresistive effect element 1102, a tunnel magnetoresistive effect element 1102, and the tunnel magnetoresistive effect element 1102 And a gate electrode 1104 for transmitting a signal for controlling ON / OFF of the current of the selection transistor 1101.

磁気ランダムアクセスメモリ１１０５は、磁気メモリセル１１００をアレイ状に複数配置したもので、各磁気メモリセル１１００の電極１１０３及びゲート電極１１０４にはそれぞれビット線１１０６及びワード線１１０７が接続されている。各ビット線１１０６及びワード線には、それぞれビット線ドライバ１１０８及びワード線ドライバ１１０９が接続されており、ワード線ドライバ１１０９から所望の選択トランジスタに制御信号を送り選択トランジスタをＯＮにすること、またビット線ドライバ１１０８から所望のメモリセルに読み出し又は書き込み電流を流すことが可能である。このようにして目的のメモリセルに接続されているワード線１１０７及びビット線１１０６を選択することにより、所望の磁気メモリセル１１００への書き込み、読み出しが可能となる。 The magnetic random access memory 1105 includes a plurality of magnetic memory cells 1100 arranged in an array. A bit line 1106 and a word line 1107 are connected to the electrode 1103 and the gate electrode 1104 of each magnetic memory cell 1100, respectively. A bit line driver 1108 and a word line driver 1109 are connected to each bit line 1106 and each word line, respectively, and a control signal is sent from the word line driver 1109 to a desired selection transistor to turn on the selection transistor. A read or write current can be supplied from the line driver 1108 to a desired memory cell. By selecting the word line 1107 and the bit line 1106 connected to the target memory cell in this manner, writing to and reading from the desired magnetic memory cell 1100 can be performed.

書き込み動作時に加熱を利用する従来のトンネル磁気抵抗効果素子の読み出し動作時と書き込み動作時における磁化配列の模式図。The schematic diagram of the magnetization arrangement | sequence in the time of read-out operation | movement at the time of read-out operation | movement of the conventional tunnel magnetoresistive effect element using a heating at the time of write-in operation | movement. 本発明のトンネル磁気抵抗効果素子の構成例を示した図。The figure which showed the structural example of the tunnel magnetoresistive effect element of this invention. 本発明のトンネル磁気抵抗効果素子の構成例を示した図。The figure which showed the structural example of the tunnel magnetoresistive effect element of this invention. 本発明のトンネル磁気抵抗効果素子において強磁性記録層に用いるフェリ磁性体の磁気特性の模式図であり、（ａ）は磁化の温度依存性を示した図、（ｂ）はダンピング定数の温度依存性図、（ｃ）は保磁力の温度依存性、（ｄ）は磁化補償温度より低温における磁化状態の模式図、（ｅ）は磁化補償温度における磁化状態の模式図、（ｆ）は磁化補償温度より高温における磁化状態の模式図。FIG. 2 is a schematic diagram of magnetic characteristics of a ferrimagnetic material used for a ferromagnetic recording layer in the tunnel magnetoresistive element of the present invention, where (a) shows the temperature dependence of magnetization, and (b) shows the temperature dependence of the damping constant. (C) is the temperature dependence of the coercive force, (d) is a schematic diagram of the magnetization state at a temperature lower than the magnetization compensation temperature, (e) is a schematic diagram of the magnetization state at the magnetization compensation temperature, and (f) is the magnetization compensation. The schematic diagram of the magnetization state in temperature higher than temperature. 本発明のトンネル磁気抵抗効果素子における読み出し動作時の磁化状態、及び書き込み動作時の磁化状態の模式図。The schematic diagram of the magnetization state at the time of read-out operation | movement and the magnetization state at the time of write-in operation | movement in the tunnel magnetoresistive effect element of this invention. 書き込み方法の一例を示す図。The figure which shows an example of the writing method. 読み出し電流と誤書き込みの確率の関係を示す図。The figure which shows the relationship between the read-out electric current and the probability of incorrect writing. 本発明のトンネル磁気抵抗効果素子の構成例を示した図。The figure which showed the structural example of the tunnel magnetoresistive effect element of this invention. 本発明のトンネル磁気抵抗効果素子の構成例を示した図。The figure which showed the structural example of the tunnel magnetoresistive effect element of this invention. 本発明のトンネル磁気抵抗効果素子の構成例を示した図。The figure which showed the structural example of the tunnel magnetoresistive effect element of this invention. 本発明のトンネル磁気抵抗効果素子を用いた磁気メモリセルと磁気ランダムアクセスメモリの構成例を示した図。The figure which showed the structural example of the magnetic memory cell and magnetic random access memory using the tunnel magnetoresistive effect element of this invention.

Explanation of symbols

１００…強磁性固定相、１０１…絶縁層、１０２…強磁性記録層、２００…トンネル磁気抵抗効果素子、２０１…配向制御膜、２０２…反強磁性膜、２０３…強磁性固定層、２０４…絶縁膜、２０５…強磁性記録層、２０６…第一の強磁性膜、２０７…第一の非磁性導電膜、２０８…第二の強磁性膜、２０９…第四の強磁性膜、２１０…第二の非磁性導電膜、２１１…第三の強磁性膜、３００…トンネル磁気抵抗素、５００…強磁性記録層、５０１…第一の強磁性膜、５０２…第一の非磁性導電膜、５０３…第二の強磁性膜、６００…トンネル磁気抵抗効果素子、６０１…加熱電流、６０２…書き込み電流、８００…トンネル磁気抵抗効果素子、８０１…配向制御膜、８０２…反強磁性膜、８０３…強磁性固定層、８０４…絶縁膜、８０５…強磁性記録層、８０６…第一の強磁性膜、８０７…第一の非磁性導電膜、８０８…第二の強磁性膜、８０９…第四の強磁性膜、８１０…第二の非磁性導電膜、８１１…第三の強磁性膜、９００…トンネル磁気抵抗効果素子、９０１…配向制御膜、９０２…反強磁性膜、９０３…強磁性固定層、９０４…絶縁膜、９０５…強磁性記録層、９０６…第一の強磁性膜、９０７…第一の非磁性導電膜、９０８…第二の強磁性膜、９０９…第四の強磁性膜、９１０…第二の非磁性導電膜、９１１…第三の強磁性膜、１０００…トンネル磁気抵抗効果素子、１００１…配向制御膜、１００２…反強磁性膜、１００３…強磁性記録層、１００４…絶縁膜、１００５…強磁性記録層、１００６…第四の強磁性膜、１００７…第二の非磁性導電膜、１００８…第三の強磁性膜、１００９…加熱層、１１００…磁気メモリセル、１１０１…選択トランジスタ、１１０２…トンネル磁気抵抗効果素子、１１０３…電極、１１０４…ゲート電極、１１０５…磁気ランダムアクセスメモリ、１１０６…ビット線、１１０７…ワード線、１１０８…ビット線ドライバ、１１０９…ワード線ドライバ DESCRIPTION OF SYMBOLS 100 ... Ferromagnetic fixed phase, 101 ... Insulating layer, 102 ... Ferromagnetic recording layer, 200 ... Tunneling magnetoresistive effect element, 201 ... Orientation control film, 202 ... Antiferromagnetic film, 203 ... Ferromagnetic fixed layer, 204 ... Insulation Film 205 ... ferromagnetic recording layer 206 ... first ferromagnetic film 207 ... first nonmagnetic conductive film 208 ... second ferromagnetic film 209 ... fourth ferromagnetic film 210 ... second Nonmagnetic conductive film 211, third ferromagnetic film, 300 tunnel magnetoresistive element, 500 ferromagnetic recording layer, 501 first ferromagnetic film, 502 first nonmagnetic conductive film, 503 Second ferromagnetic film, 600 ... tunnel magnetoresistive effect element, 601 ... heating current, 602 ... write current, 800 ... tunnel magnetoresistive effect element, 801 ... orientation control film, 802 ... antiferromagnetic film, 803 ... ferromagnetic Fixed layer, 804 ... insulating film, 805 ... Magnetic recording layer, 806 ... first ferromagnetic film, 807 ... first nonmagnetic conductive film, 808 ... second ferromagnetic film, 809 ... fourth ferromagnetic film, 810 ... second nonmagnetic conductive film , 811 ... third ferromagnetic film, 900 ... tunnel magnetoresistive element, 901 ... orientation control film, 902 ... antiferromagnetic film, 903 ... ferromagnetic fixed layer, 904 ... insulating film, 905 ... ferromagnetic recording layer, 906 ... first ferromagnetic film, 907 ... first nonmagnetic conductive film, 908 ... second ferromagnetic film, 909 ... fourth ferromagnetic film, 910 ... second nonmagnetic conductive film, 911 ... first Three ferromagnetic films, 1000 ... tunnel magnetoresistive effect element, 1001 ... orientation control film, 1002 ... antiferromagnetic film, 1003 ... ferromagnetic recording layer, 1004 ... insulating film, 1005 ... ferromagnetic recording layer, 1006 ... fourth Ferromagnetic film 1007 second nonmagnetic conductive film 1008 first Ferromagnetic film, 1009 ... heating layer, 1100 ... magnetic memory cell, 1101 ... selection transistor, 1102 ... tunnel magnetoresistive effect element, 1103 ... electrode, 1104 ... gate electrode, 1105 ... magnetic random access memory, 1106 ... bit line, 1107: Word line, 1108: Bit line driver, 1109: Word line driver

Claims

An insulating film, and a ferromagnetic recording layer and a ferromagnetic pinned layer sandwiched between the insulating films,
The ferromagnetic recording layer is composed of a first ferromagnetic film and a second ferromagnetic film provided with a nonmagnetic conductive layer interposed therebetween,
The second ferromagnetic film is a ferrimagnetic material,
In the ferrimagnetic material, the angular momentum compensation temperature is in the vicinity of the temperature during the read operation and becomes higher than the angular momentum compensation temperature during the write operation,
The magnetizations of the first ferromagnetic film and the second ferromagnetic film are exchange coupled,
The tunnel magnetoresistive effect element characterized in that the magnetization directions of the first ferromagnetic film and the second ferromagnetic film are opposite to each other at a temperature higher than the angular momentum compensation temperature.

2. The tunnel magnetoresistive element according to claim 1, wherein a damping constant at a temperature when a read current is passed through the ferrimagnetic material is larger than a damping constant at a temperature when a write current is passed. .

3. The tunnel magnetoresistive effect element according to claim 1, wherein a heating layer is provided adjacent to the ferromagnetic recording layer to generate heat by energizing a write current and heat the second ferromagnetic film. A tunnel magnetoresistive effect element.

A tunnel magnetoresistive effect element having an insulating film, and a ferromagnetic recording layer and a ferromagnetic pinned layer sandwiched between the insulating films ;
An electrode for passing a current through the tunnel magnetoresistive element;
A switching element that controls on / off of the current flowing through the tunnel magnetoresistive element,
In a magnetic memory cell in which the magnetization of the ferromagnetic recording layer can be reversed by a spin transfer torque ,
Before SL ferromagnetic recording layer is made from a first ferromagnetic film and a second ferromagnetic film provided across the non-magnetic conductive layer,
The second ferromagnetic film is a ferrimagnetic material,
In the ferrimagnetic material, the angular momentum compensation temperature is in the vicinity of the temperature during the read operation and becomes higher than the angular momentum compensation temperature during the write operation,
The magnetizations of the first ferromagnetic film and the second ferromagnetic film are exchange coupled,
The magnetic memory cell according to claim 1, wherein magnetization directions of the first ferromagnetic film and the second ferromagnetic film are opposite to each other at a temperature higher than the angular momentum compensation temperature.

5. The magnetic memory cell according to claim 4, wherein a damping constant at a temperature when the read current is supplied to the ferrimagnetic material is larger than a damping constant at a temperature when the write current is supplied.

5. The magnetic memory cell according to claim 4, wherein a write current for reversing the magnetization direction of the ferromagnetic recording layer is applied by spin transfer torque after applying a current for heating to the tunnel magnetoresistive effect element at the time of writing. A magnetic memory cell that is applied.

A plurality of magnetic memory cells;
Means for selecting a desired magnetic memory cell from the plurality of magnetic memory cells;
In a magnetic random access memory comprising means for reading or writing information to the selected magnetic memory cell,
The magnetic memory cell includes a tunnel magnetoresistive effect element having an insulating film, a ferromagnetic recording layer provided between the insulating film and a ferromagnetic pinned layer, and an electrode for passing a current through the tunnel magnetoresistive effect element And a switching element that controls on / off of the current flowing through the tunnel magnetoresistive effect element, the magnetization of the ferromagnetic recording layer can be reversed by a spin transfer torque ,
Before SL ferromagnetic recording layer, made from a first ferromagnetic film and a second ferromagnetic film provided across the non-magnetic conductive layer, the second ferromagnetic film is a ferrimagnetic material, the ferrimagnetic In the magnetic material, the angular momentum compensation temperature is close to the temperature during the read operation and becomes higher than the angular momentum compensation temperature during the write operation, and the magnetizations of the first ferromagnetic film and the second ferromagnetic film are exchanged. A magnetic random access memory which is coupled and wherein the magnetization directions of the first ferromagnetic film and the second ferromagnetic film are opposite to each other at a temperature higher than the angular momentum compensation temperature.

8. The magnetic random access memory according to claim 7, wherein a damping constant at a temperature when a read current is supplied to the ferrimagnetic material is larger than a damping constant at a temperature when a write current is supplied.