JPH09251618A - Magnetic sensor - Google Patents
Magnetic sensorInfo
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- JPH09251618A JPH09251618A JP6220196A JP6220196A JPH09251618A JP H09251618 A JPH09251618 A JP H09251618A JP 6220196 A JP6220196 A JP 6220196A JP 6220196 A JP6220196 A JP 6220196A JP H09251618 A JPH09251618 A JP H09251618A
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Abstract
(57)【要約】
【課題】 磁界を検出する磁気センサ、特に、スピント
ンネル現象を利用した磁気センサに関し、信号対雑音比
を向上し、磁界感度の高い磁気センサを提供する。
【解決手段】 磁気センサの基本構造は、反強磁性材料
からなる反強磁性体層１１、保磁力の大きな強磁性材料
からなる強磁性体層１２、絶縁材料からなる絶縁体層１
３、保磁力の小さな軟磁性材料からなる軟磁性体層１
４、絶縁体層１５、保磁力の大きな強磁性材料からなる
強磁性体層１６、反強磁性材料からなる反強磁性体層１
７が順番に積層された積層体１０である。強磁性体層１
２と軟磁性体層１４とによりトンネル接合が構成され、
強磁性体層１６と軟磁性体層１４とによりトンネル接合
が構成される。
Kind Code: A1 A magnetic sensor for detecting a magnetic field, particularly a magnetic sensor utilizing a spin tunneling phenomenon, is provided, and a magnetic sensor having an improved signal-to-noise ratio and high magnetic field sensitivity is provided. SOLUTION: The basic structure of a magnetic sensor is an antiferromagnetic layer 11 made of an antiferromagnetic material, a ferromagnetic layer 12 made of a ferromagnetic material having a large coercive force, and an insulating layer 1 made of an insulating material.
3. Soft magnetic layer 1 made of soft magnetic material with small coercive force
4, the insulator layer 15, the ferromagnetic layer 16 made of a ferromagnetic material having a large coercive force, and the antiferromagnetic layer 1 made of an antiferromagnetic material.
7 is a laminated body 10 which is laminated in order. Ferromagnetic layer 1
2 and the soft magnetic layer 14 form a tunnel junction,
The ferromagnetic material layer 16 and the soft magnetic material layer 14 form a tunnel junction.
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、磁界を検出する磁
気センサ、特に、スピントンネル現象を利用した磁気セ
ンサに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor for detecting a magnetic field, and more particularly to a magnetic sensor utilizing the spin tunnel phenomenon.
【０００２】[0002]
【従来の技術】近年の磁気記録技術の高密度化にともな
い、磁気記録媒体と読取ヘッドとの相対的速度が非常に
低下してきている。このため、従来の電磁誘導型磁気ヘ
ッドでは十分な読取出力を得ることが困難になってきて
いる。相対的速度が低下しても高い読取出力を得ること
ができる磁気センサとして、磁気抵抗効果を利用した磁
気抵抗型（ＭＲ型）磁気センサや、スピントンネル現象
を利用したスピントンネル型磁気センサ等が提案されて
いる。2. Description of the Related Art With the recent increase in the density of magnetic recording technology, the relative speed between a magnetic recording medium and a read head has decreased significantly. Therefore, it has become difficult to obtain a sufficient read output with the conventional electromagnetic induction type magnetic head. As a magnetic sensor that can obtain a high read output even if the relative speed decreases, a magnetoresistive (MR) magnetic sensor utilizing a magnetoresistive effect, a spin tunneling magnetic sensor utilizing a spin tunneling phenomenon, and the like are available. Proposed.
【０００３】スピントンネル型磁気センサは、２つの磁
性体層により絶縁体層を挟んだ磁性体層／絶縁体層／磁
性体層の積層体を有しており、磁性体層間に電圧を印加
し、電子をトンネリングさせたとき、両磁性体層の磁化
方向の相対角度に基づいて、電子のトンネリング確率が
変化する現象を利用している。電子を供給する一方の磁
性体層の電子スピンが分極しており、この分極状態を保
ったまま電子がトンネルするため、両磁性体層の磁化方
向の相対角度に応じて電子のトンネリング確率が変化す
る。A spin tunnel magnetic sensor has a laminated body of a magnetic layer / insulator layer / magnetic layer in which an insulating layer is sandwiched by two magnetic layers, and a voltage is applied between the magnetic layers. , When an electron is tunneled, the phenomenon that the tunneling probability of the electron changes based on the relative angle of the magnetization directions of both magnetic layers is used. The electron spin of one magnetic layer that supplies electrons is polarized, and the electrons tunnel while maintaining this polarization state, so the tunneling probability of electrons changes depending on the relative angle of the magnetization direction of both magnetic layers. To do.
【０００４】従来のスピントンネル型磁気センサとして
は、第１強磁性薄膜と第２強磁性薄膜により絶縁膜を挟
んで接合するものが一般的である。特開平６−２４４７
７号公報には、第１強磁性薄膜と第２強磁性薄膜とをス
トライプ状にパターニングして磁化容易軸を互いに直交
させ、第１強磁性薄膜の磁化容易軸方向の保磁力を第２
強磁性薄膜の磁化容易軸方向の保磁力より２倍以上大き
くした磁気センサが提案されている。外部磁場により保
磁力の小さな第２強磁性薄膜の磁化を回転すると、第１
強磁性薄膜から第２強磁性薄膜へのトンネル電流が変化
する。A conventional spin tunneling magnetic sensor is generally one in which an insulating film is sandwiched between a first ferromagnetic thin film and a second ferromagnetic thin film and bonded. Japanese Patent Laid-Open No. 6-2447
No. 7, in which the first ferromagnetic thin film and the second ferromagnetic thin film are patterned in stripes so that the easy magnetization axes are orthogonal to each other, and the coercive force of the first ferromagnetic thin film in the easy magnetization axis direction is set to the second
A magnetic sensor has been proposed in which the coercive force of the ferromagnetic thin film in the direction of the easy axis is at least twice as large. When the magnetization of the second ferromagnetic thin film having a small coercive force is rotated by an external magnetic field,
The tunnel current from the ferromagnetic thin film to the second ferromagnetic thin film changes.
【０００５】また、強磁性薄膜の材料として、異方性磁
気抵抗効果が小さく、強磁性トンネル効果が大きく現れ
るＦｅ系合金を用いることが提案されている（中谷、北
田、日本金属学会秋期大会講演概要、ｐ．３６４、１９
９４）。更に、強磁性薄膜の保磁力に差をつけるため、
Ｆｅ系合金にＣ（炭素）やＲｕ（ルテニウム）を添加し
たり、成膜時の基板温度を変えたりすることが行われて
いる。As a material for the ferromagnetic thin film, it has been proposed to use an Fe-based alloy exhibiting a small anisotropic magnetoresistance effect and a large ferromagnetic tunnel effect (Nakaya, Kitada, Autumn Meeting of the Japan Institute of Metals). Overview, p.364, 19
94). Furthermore, in order to make a difference in the coercive force of the ferromagnetic thin film,
C (carbon) and Ru (ruthenium) are added to the Fe-based alloy, and the substrate temperature during film formation is changed.
【０００６】また、他のスピントンネル型磁気センサと
して、多層磁性薄膜を用いたものが知られている。特開
平３−２６６４８１号公報には、Ｆｅ層に常磁性で非絶
縁物の中間層を介して多層構造にした磁気抵抗効果素子
が提案されている。消磁状態でＦｅ層の磁化方向を上下
で反平行にし、Ｆｅ層の層数を４層以上にすることによ
り、低い印加磁界でも抵抗変化を示す。As another spin tunnel magnetic sensor, one using a multilayer magnetic thin film is known. Japanese Unexamined Patent Publication (Kokai) No. 3-266481 proposes a magnetoresistive element having a multi-layered structure in which a paramagnetic non-insulating intermediate layer is formed in the Fe layer. In the demagnetized state, the magnetization directions of the Fe layers are vertically antiparallel, and the number of Fe layers is four or more, so that the resistance changes even in a low applied magnetic field.
【０００７】特開平７−７４０２２号公報には、硬磁性
層、反強磁性層に接する軟磁性層、反強磁性層に接して
いない軟磁性層をそれぞれ非磁性層を介して積層した多
層構造の磁気抵抗効果膜を使用した磁気ヘッドが開示さ
れている。２層の磁性層を有する多層膜により高い磁気
抵抗効果を示す。特開平６−２２３３３６号公報には、
非磁性金属の層で相互に分離された第１、第２及び第３
の強磁性体層を有する磁気抵抗読取センサが提供されて
いる。第１及び第３の強磁性体層の磁化方向は固定され
ており、中間の第２の強磁性体層は軟磁性であり、印加
磁界がないときは磁化方向が両側の第１及び第３の強磁
性体層の磁化方向に対して垂直である多層２重スピンバ
ルブ構造をしている。この構造によれば、いずれの方向
に散乱する伝導電子も利用することができるので、低い
印加磁界でも高い磁気抵抗効果を示す。Japanese Unexamined Patent Publication No. 7-74022 discloses a multi-layer structure in which a hard magnetic layer, a soft magnetic layer in contact with an antiferromagnetic layer, and a soft magnetic layer not in contact with an antiferromagnetic layer are laminated via nonmagnetic layers. Discloses a magnetic head using the magnetoresistive film. A multi-layer film having two magnetic layers exhibits a high magnetoresistive effect. Japanese Patent Laid-Open No. 6-223336 discloses that
First, second and third separated from each other by a layer of non-magnetic metal
A magnetoresistive read sensor having a ferromagnetic layer is provided. The magnetization directions of the first and third ferromagnetic layers are fixed, the second ferromagnetic layer in the middle is soft magnetic, and when there is no applied magnetic field, the magnetization directions of both sides are the first and the third. Has a multilayer double spin-valve structure perpendicular to the magnetization direction of the ferromagnetic layer. According to this structure, since the conduction electrons scattered in any direction can be used, a high magnetoresistive effect is exhibited even in a low applied magnetic field.
【０００８】[0008]
【発明が解決しようとする課題】このように、スピント
ンネル現象を利用した様々な磁気センサが提案されてい
るが、スピントンネル現象による電圧変化は微小である
上に、記録媒体からの信号はますます微弱になってきて
おり、磁気センサの出力を高め、ノイズを低減すること
が重要な課題となってきている。As described above, various magnetic sensors utilizing the spin tunneling phenomenon have been proposed, but the voltage change due to the spin tunneling phenomenon is minute and the signal from the recording medium is small. It is becoming weaker, and increasing the output of the magnetic sensor and reducing noise are becoming important issues.
【０００９】本発明の目的は、上述した課題を克服し、
信号対雑音比を向上し、磁界感度の高い磁気センサを提
供することにある。The object of the present invention is to overcome the above-mentioned problems,
An object is to provide a magnetic sensor having an improved signal-to-noise ratio and high magnetic field sensitivity.
【００１０】[0010]
【課題を解決するための手段】上記目的は、磁化容易軸
が第１の方向である第１の磁性体層と、磁化容易軸が前
記第１の方向と異なる第２の方向である第２の磁性体層
と、前記第１の磁性体層と前記第２の磁性体層の間に位
置し、前記第１の磁性体層及び前記第２の磁性体層より
も保磁力の小さい第３の磁性体層と、前記第１の磁性体
層と前記第３の磁性体層の間に挿入された第１の絶縁体
層と、前記第２の磁性体層と前記第３の磁性体層の間に
挿入された第２の絶縁体層とを有し、前記第１の磁性体
層と前記第３の磁性体層間のトンネル抵抗と、前記第２
の磁性体層と前記第３の磁性体層間のトンネル抵抗とに
基づいて外部磁界を検出することを特徴とする磁気セン
サによって達成される。The above-mentioned object is to provide a first magnetic layer having an easy axis of magnetization in a first direction, and a second magnetic layer having a easy axis of magnetization in a second direction different from the first direction. Magnetic layer, and a third magnetic layer having a coercive force smaller than that of the first magnetic layer and the second magnetic layer, the third magnetic layer being located between the first magnetic layer and the second magnetic layer. Magnetic material layer, a first insulator layer inserted between the first magnetic material layer and the third magnetic material layer, the second magnetic material layer and the third magnetic material layer A second insulating layer inserted between the first magnetic layer and the third magnetic layer;
And an external magnetic field based on the tunnel resistance between the magnetic layer and the third magnetic layer.
【００１１】上述した磁気センサにおいて、前記第１の
方向と前記第２の方向とはほぼ反対向きであることが望
ましい。上述した磁気センサにおいて、前記第３の磁性
体層の磁化容易軸が、前記第１の方向と前記第２の方向
とそれぞれほぼ直交していることが望ましい。上述した
磁気センサにおいて、前記第１の磁性体層と前記第２の
磁性体層の少なくとも一方の層に、磁化容易軸方向をピ
ンニングするための反強磁性体層を設けたことが望まし
い。In the above magnetic sensor, it is desirable that the first direction and the second direction are substantially opposite to each other. In the magnetic sensor described above, it is preferable that the easy magnetization axis of the third magnetic layer is substantially orthogonal to the first direction and the second direction. In the magnetic sensor described above, it is preferable that an antiferromagnetic layer for pinning the easy axis of magnetization is provided on at least one of the first magnetic layer and the second magnetic layer.
【００１２】上述した磁気センサにおいて、前記第１の
磁性体層及び前記第２の磁性体層の保磁力が、前記第３
の磁性体層の磁化困難軸方向の飽和磁場よりも大きいこ
とが望ましい。上述した磁気センサにおいて、前記第１
の磁性体層による静磁界と前記第２の磁性体層による静
磁界とが前記第３の磁性体層において互いに相殺されて
いることが望ましい。In the above magnetic sensor, the coercive forces of the first magnetic layer and the second magnetic layer are the same as those of the third magnetic layer.
It is desirable that the magnetic field is larger than the saturation magnetic field in the hard axis direction of the magnetic layer. In the magnetic sensor described above, the first
It is desirable that the static magnetic field generated by the magnetic layer and the static magnetic field generated by the second magnetic layer cancel each other out in the third magnetic layer.
【００１３】上述した磁気センサにおいて、前記第１の
磁性体層と前記第３の磁性体層間のトンネル抵抗に基づ
く第１の電気信号と、前記第２の磁性体層と前記第３の
磁性体層間のトンネル抵抗に基づく第２の電気信号との
差分を検出する差分検出手段を有することが望ましい。In the above magnetic sensor, a first electric signal based on a tunnel resistance between the first magnetic layer and the third magnetic layer, the second magnetic layer and the third magnetic layer. It is desirable to have a difference detecting means for detecting a difference from the second electric signal based on the tunnel resistance between the layers.
【００１４】[0014]
【発明の実施の形態】本発明の一実施形態による磁気セ
ンサを図１乃至図３を用いて説明する。図１は本実施形
態の磁気センサの基本構造を示す図であり、図２は本実
施形態の磁気センサの検出回路の回路図であり、図３及
び図４は本実施形態の磁気センサにおける外部磁場に対
する磁気抵抗及び再生信号出力の変化を示すグラフであ
る。DETAILED DESCRIPTION OF THE INVENTION A magnetic sensor according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a basic structure of the magnetic sensor of the present embodiment, FIG. 2 is a circuit diagram of a detection circuit of the magnetic sensor of the present embodiment, and FIGS. 3 and 4 are external views of the magnetic sensor of the present embodiment. 7 is a graph showing changes in magnetic resistance and reproduction signal output with respect to a magnetic field.
【００１５】本実施形態の磁気センサの基本構造は、図
１に示すように、反強磁性材料からなる反強磁性体層１
１、保磁力の大きな強磁性材料からなる強磁性体層１
２、絶縁材料からなる絶縁体層１３、保磁力の小さな軟
磁性材料からなる軟磁性体層１４、絶縁体層１５、保磁
力の大きな強磁性材料からなる強磁性体層１６、反強磁
性材料からなる反強磁性体層１７が順番に積層された積
層体１０である。強磁性体層１２と軟磁性体層１４とに
よりトンネル接合が構成され、強磁性体層１６と軟磁性
体層１４とによりトンネル接合が構成される。The basic structure of the magnetic sensor of this embodiment is, as shown in FIG. 1, an antiferromagnetic material layer 1 made of an antiferromagnetic material.
1. Ferromagnetic layer 1 made of a ferromagnetic material with a large coercive force
2. Insulator layer 13 made of insulating material, soft magnetic layer 14 made of soft magnetic material having small coercive force, insulator layer 15, ferromagnetic layer 16 made of ferromagnetic material having large coercive force, antiferromagnetic material The antiferromagnetic material layer 17 is formed in this order in the laminated body 10. The ferromagnetic layer 12 and the soft magnetic layer 14 form a tunnel junction, and the ferromagnetic layer 16 and the soft magnetic layer 14 form a tunnel junction.
【００１６】反強磁性体層１１は約２５ｎｍ厚のＮｉＭ
ｎからなり、強磁性体層１２は約２０ｎｍ厚のＦｅから
なり、絶縁体層１３は約２ｎｍ厚のＡｌ2Ｏ3からなり、
軟磁性体層１４は約２０ｎｍ厚のＮｉＦｅからなり、絶
縁体層１５は約２ｎｍ厚のＡｌ2Ｏ3からなり、強磁性体
層１６は約２０ｎｍ厚のＦｅからなり、反強磁性体層１
７は約２０ｎｍ厚のＦｅＭｎからなる。The antiferromagnetic layer 11 is made of NiM having a thickness of about 25 nm.
the ferromagnetic layer 12 is made of Fe having a thickness of about 20 nm, and the insulating layer 13 is made of Al 2 O 3 having a thickness of about 2 nm.
The soft magnetic layer 14 is made of NiFe having a thickness of about 20 nm, the insulator layer 15 is made of Al 2 O 3 having a thickness of about 2 nm, and the ferromagnetic layer 16 is made of Fe having a thickness of about 20 nm.
7 is made of FeMn having a thickness of about 20 nm.
【００１７】なお、反強磁性体層１１、１７としては、
他の反強磁性材料、例えば、不規則合金のＦｅＭｎ、規
則合金のＮｉＭｎ、ＰｄＭｎ、ＰｔＭｎ、ＮａＣｌ構造
のＭｎＯ、ＮｉＯ等でもよい。強磁性体層１２、１６と
しては、他の強磁性材料、例えば、保磁力が約５０Ｏｅ
（エルステッド）以上のＣｏ、Ｎｉや、Ｆｅ、Ｃｏ、Ｎ
ｉ等の合金等でもよい。軟磁性体層１４としては、他の
軟磁性材料、例えば、保磁力が約１０Ｏｅ以下のＣｏＦ
ｅ合金等でもよい。絶縁体層１３、１５としては、他の
絶縁体、例えば、ＳｉＯ2、ＡｌＮ、ＮｉＯ、ＣｏＯ等
でもよい。As the antiferromagnetic material layers 11 and 17,
Other antiferromagnetic materials such as disordered alloy FeMn, ordered alloy NiMn, PdMn, PtMn, and NaCl structure MnO and NiO may be used. The ferromagnetic layers 12 and 16 are made of another ferromagnetic material, for example, having a coercive force of about 50 Oe.
(Oersted) or higher Co, Ni, Fe, Co, N
An alloy such as i may be used. As the soft magnetic layer 14, another soft magnetic material such as CoF having a coercive force of about 10 Oe or less is used.
e alloy or the like may be used. The insulator layers 13 and 15 may be made of another insulator such as SiO 2 , AlN, NiO, CoO or the like.
【００１８】反強磁性体層１１は、図１に示すように、
強磁性体層１２の磁化方向を紙面の表から裏に向かう方
向にピンニングし、反強磁性体層１７は、強磁性体層１
６の磁化方向を、紙面の裏から表に向かう方向にピンニ
ングする。これにより、強磁性体層１２と強磁性体層１
６は互いに反対方向に磁化がピンニングされる。軟磁性
体層１４は、保磁力が小さく外部磁場に応じて自由に磁
化の向きが回転する。軟磁性体層１４の磁化容易軸の方
向は、強磁性体層１２の磁化方向と強磁性体層１６の磁
化方向にほぼ直交している。軟磁性体層１４の磁化困難
軸方向の飽和磁場は約５Ｏｅであり、強磁性体層１２と
強磁性体層１６の保磁力（約３０Ｏｅ）より小さいこと
が望ましい。The antiferromagnetic material layer 11 is, as shown in FIG.
The magnetization direction of the ferromagnetic layer 12 is pinned in the direction from the front side to the back side of the drawing, and the antiferromagnetic layer 17 is the ferromagnetic layer 1.
The magnetization direction of 6 is pinned in the direction from the back of the paper to the front. Thereby, the ferromagnetic layer 12 and the ferromagnetic layer 1
6, the magnetizations are pinned in opposite directions. The soft magnetic layer 14 has a small coercive force, and its magnetization direction freely rotates in response to an external magnetic field. The direction of the easy axis of magnetization of the soft magnetic layer 14 is substantially orthogonal to the magnetization direction of the ferromagnetic layer 12 and the magnetization direction of the ferromagnetic layer 16. The saturation magnetic field of the soft magnetic layer 14 in the hard axis direction is about 5 Oe, which is preferably smaller than the coercive force of the ferromagnetic layers 12 and 16 (about 30 Oe).
【００１９】強磁性体層１２と強磁性体層１６の強磁性
材料及び膜厚を調整することにより、強磁性体層１２に
よる静磁界と強磁性体層１６による静磁界が軟磁性体層
１４において互いに相殺するようにできる。これにより
軟磁性体層１４は、静磁エネルギを生ずることなく、外
部磁界に応じて自己の磁化の向きを変えることができ
る。By adjusting the ferromagnetic materials and the film thicknesses of the ferromagnetic layers 12 and 16, the static magnetic field generated by the ferromagnetic layer 12 and the static magnetic field generated by the ferromagnetic layer 16 are changed to the soft magnetic layer 14. Can cancel each other out in. Thereby, the soft magnetic layer 14 can change its own magnetization direction according to the external magnetic field without generating magnetostatic energy.
【００２０】本発明の一実施形態による磁気センサの再
生信号の検出回路を図２を用いて説明する。磁気センサ
の積層体１０の強磁性体層１６と軟磁性体層１４間のト
ンネル接合の抵抗をｒ1、軟磁性体層１４と強磁性体層
１２間のトンネル接合の抵抗をｒ2とすると、外部磁場
により軟磁性体層１４の磁化方向が変化すると、スピン
トンネル現象により抵抗ｒ1、ｒ2が変化する。A reproduction signal detection circuit of the magnetic sensor according to the embodiment of the present invention will be described with reference to FIG. When the resistance of the tunnel junction between the ferromagnetic layer 16 and the soft magnetic layer 14 of the laminated body 10 of the magnetic sensor is r1, and the resistance of the tunnel junction between the soft magnetic layer 14 and the ferromagnetic layer 12 is r2, the external When the magnetization direction of the soft magnetic layer 14 changes due to the magnetic field, the resistances r1 and r2 change due to the spin tunneling phenomenon.
【００２１】外部磁場が印加され、軟磁性体層１４の磁
化の向きが回転すると、一方のトンネル接合の抵抗ｒ1
又はｒ2が大きくなり、他方のトンネル接合の抵抗ｒ2又
はｒ1が小さくなる相補的な変化をする。本実施形態で
は、このような相補的に変化する抵抗の変化の差分をと
ることにより、磁界検出感度を高くすると共に、同位相
で発生する雑音成分を効果的に除去して、信号対雑音比
を飛躍的に向上する。When an external magnetic field is applied and the direction of magnetization of the soft magnetic layer 14 rotates, the resistance r1 of one tunnel junction is increased.
Or, r2 becomes larger and the resistance r2 or r1 of the other tunnel junction becomes smaller, which is a complementary change. In the present embodiment, by taking the difference between the resistance changes that change complementarily as described above, the magnetic field detection sensitivity is increased, and the noise component generated in the same phase is effectively removed to obtain a signal-to-noise ratio. To dramatically improve.
【００２２】直流電源Ｅにより軟磁性体層１４に正の電
圧Ｅを印加し、強磁性体層１６と軟磁性体層１４間に流
れる電流ｉ1をオペアンプＯＰ１により増幅し、強磁性
体層１２と軟磁性体層１４間に流れる電流ｉ2をオペア
ンプＯＰ２により増幅する。オペアンプＯＰ１、ＯＰ２
の出力Ｖ1、Ｖ2は、次式のようになる。 Ｖ1＝α1×ｉ1＝α1×Ｅ／ｒ1 Ｖ2＝α2×ｉ2＝α2×Ｅ／ｒ2 ただし、α1はオペアンプＯＰ１の増幅率 α2はオペアンプＯＰ２の増幅率 オペアンプＯＰ１、ＯＰ２の出力Ｖ1、Ｖ2は、それぞれ
抵抗Ｒ1、Ｒ2を介して接地されている。オペアンプＯＰ
１、ＯＰ２の出力Ｖ1、Ｖ2は、オペアンプＯＰ３により
差動増幅され、再生出力信号Ｖoutは、次式のようにな
る。A positive voltage E is applied to the soft magnetic material layer 14 by a DC power source E, and a current i1 flowing between the ferromagnetic material layer 16 and the soft magnetic material layer 14 is amplified by an operational amplifier OP1 so that the ferromagnetic material layer 12 and The current i2 flowing between the soft magnetic layers 14 is amplified by the operational amplifier OP2. Operational amplifiers OP1 and OP2
The outputs V1 and V2 of the above equation are as follows. V1 = α1 × i1 = α1 × E / r1 V2 = α2 × i2 = α2 × E / r2 where α1 is the amplification factor of the operational amplifier OP1, α2 is the amplification factor of the operational amplifier OP2, and the outputs V1 and V2 of the operational amplifiers OP1 and OP2 are respectively It is grounded via resistors R1 and R2. Operational amplifier OP
The outputs V1 and V2 of 1 and OP2 are differentially amplified by the operational amplifier OP3, and the reproduction output signal Vout is expressed by the following equation.
【００２３】Ｖout＝α3（Ｖ1−Ｖ2） ただし、α3はオペアンプＯＰ３の増幅率 外部磁場の変化に応じた抵抗ｒ1、ｒ2の変化を図３に示
し、再生出力信号Ｖoutの変化を図４に示す。図３及び
図４において、図１の紙面の裏から表に向かう方向の外
部磁場を正とし、反対方向の外部磁場を負とする。Vout = α3 (V1−V2) where α3 shows the change of the resistances r1 and r2 according to the change of the amplification factor of the operational amplifier OP3, and FIG. 4 shows the change of the reproduction output signal Vout. . In FIGS. 3 and 4, the external magnetic field in the direction from the back of the paper surface of FIG. 1 to the front is positive, and the external magnetic field in the opposite direction is negative.
【００２４】外部磁場が印加されない場合には、軟磁性
体層１４の磁化の向きは初期の磁化容易軸方向を向いて
おり、図３に示すように、抵抗ｒ1と抵抗ｒ2は等しい。
したがって、出力Ｖ1、Ｖ2は等しくなり、図４に示すよ
うに、再生出力Ｖoutはゼロとなる。正の外部磁場が印
加されると、軟磁性体層１４の磁化の向きは初期の磁化
容易軸方向から図１の紙面の裏から表に向かう方向に回
転する。その結果、図３に示すように、強磁性体層１６
と軟磁性体層１４間のトンネル接合の抵抗ｒ1が小さく
なり、軟磁性体層１４と強磁性体層１２間のトンネル接
合の抵抗ｒ2が大きくなる。したがって、出力Ｖ1が大き
く、出力Ｖ2が小さくなり、図４に示すように、再生出
力Ｖoutが正の値となる。正の外部磁界が大きくなると
再生出力Ｖoutも大きくなり、軟磁性体層１４の磁化が
紙面の裏から表になると、抵抗変化は終了し、再生出力
も飽和する。When no external magnetic field is applied, the magnetization direction of the soft magnetic layer 14 is in the initial easy axis direction, and the resistance r1 and the resistance r2 are equal as shown in FIG.
Therefore, the outputs V1 and V2 become equal, and the reproduction output Vout becomes zero as shown in FIG. When a positive external magnetic field is applied, the magnetization direction of the soft magnetic layer 14 rotates from the initial easy axis of magnetization to the direction from the back of the paper surface of FIG. 1 to the front. As a result, as shown in FIG.
The resistance r1 of the tunnel junction between the magnetic layer 14 and the soft magnetic layer 14 becomes small, and the resistance r2 of the tunnel junction between the soft magnetic layer 14 and the ferromagnetic layer 12 becomes large. Therefore, the output V1 is large and the output V2 is small, and as shown in FIG. 4, the reproduction output Vout has a positive value. When the positive external magnetic field becomes large, the reproduction output Vout also becomes large, and when the magnetization of the soft magnetic material layer 14 is exposed from the back side of the paper, the resistance change ends and the reproduction output is saturated.
【００２５】負の外部磁場が印加されると、軟磁性体層
１４の磁化の向きは初期の磁化容易軸方向から図１の紙
面の表から裏に向かう方向に回転する。その結果、図３
に示すように、強磁性体層１６と軟磁性体層１４間のト
ンネル接合の抵抗ｒ1が大きくなり、軟磁性体層１４と
強磁性体層１２間のトンネル接合の抵抗ｒ2が小さくな
る。したがって、出力Ｖ1が小さく、出力Ｖ2が大きくな
り、図４に示すように、再生出力Ｖoutが負の値とな
る。負の外部磁界が大きくなると再生出力Ｖoutの負の
値も大きくなり、軟磁性体層１４の磁化が紙面の表から
裏になると、抵抗変化は終了し、再生出力も飽和する。When a negative external magnetic field is applied, the direction of magnetization of the soft magnetic layer 14 rotates from the initial easy axis of magnetization to the direction from the front to the back of the paper surface of FIG. As a result, FIG.
As shown in, the resistance r1 of the tunnel junction between the ferromagnetic layer 16 and the soft magnetic layer 14 increases, and the resistance r2 of the tunnel junction between the soft magnetic layer 14 and the ferromagnetic layer 12 decreases. Therefore, the output V1 is small and the output V2 is large, and the reproduction output Vout has a negative value as shown in FIG. When the negative external magnetic field becomes large, the negative value of the reproduction output Vout also becomes large, and when the magnetization of the soft magnetic material layer 14 changes from the front to the back of the paper, the resistance change ends and the reproduction output is saturated.
【００２６】次に、本実施形態による磁気センサの製造
方法について、図５を用いて説明する。まず、例えば、
ガラス基板等の支持基板２０上に、スパタリングによ
り、反強磁性体層１１として約２５ｎｍ厚のＮｉＭｎ層
を堆積し、引き続いて、強磁性体層１２として約２０ｎ
ｍ厚のＦｅ層を堆積する（図５（ａ））。続いて、図５
（ａ）の矢印の方向（紙面の表から裏に向かう方向）に
約２０００Ｏｅの磁場を印加しながら、約３００℃の熱
処理を約１時間行う。ＮｉＭｎ層は規則化が進み、反強
磁性体に変化すると共に、Ｆｅ層の磁化方向は印加磁場
の方向にピンニングされる。Next, the method for manufacturing the magnetic sensor according to the present embodiment will be explained with reference to FIGS. First, for example,
On the supporting substrate 20 such as a glass substrate, a NiMn layer having a thickness of about 25 nm is deposited as the antiferromagnetic material layer 11 by spattering, and subsequently, a ferromagnetic material layer 12 having a thickness of about 20 n is deposited.
An Fe layer having a thickness of m is deposited (FIG. 5A). Subsequently, FIG.
While applying a magnetic field of about 2000 Oe in the direction of the arrow in (a) (direction from front to back of paper), heat treatment at about 300 ° C. is performed for about 1 hour. The NiMn layer is regularly ordered and changed to an antiferromagnetic material, and the magnetization direction of the Fe layer is pinned in the direction of the applied magnetic field.
【００２７】次に、スパッタリングにより、約５ｎｍ厚
のＡｌを堆積し、１００ｍＴｏｒｒの酸素雰囲気中で１
時間酸化処理を行うことにより絶縁体層１３を形成する
（図５（ｂ））。続いて、図５（ｂ）の矢印の方向（紙
面の左から右に向かう方向）に約１００Ｏｅの磁場を印
加しながら、スパタリングにより、軟磁性体層１４とし
て約２０ｎｍ厚のＮｉＦｅ層を堆積する。これにより軟
磁性体層１４の磁化容易軸が印加磁場の方向になる。Next, Al is deposited to a thickness of about 5 nm by sputtering, and the Al is deposited in an oxygen atmosphere of 100 mTorr.
The insulator layer 13 is formed by performing the time oxidation treatment (FIG. 5B). Subsequently, while applying a magnetic field of about 100 Oe in the direction of the arrow in FIG. 5B (the direction from the left to the right of the paper), a NiFe layer having a thickness of about 20 nm is deposited as the soft magnetic layer 14 by sputtering. . As a result, the axis of easy magnetization of the soft magnetic layer 14 becomes the direction of the applied magnetic field.
【００２８】次に、スパッタリングにより、約５ｎｍ厚
のＡｌを堆積し、酸化処理を行うことにより絶縁体層１
５を形成する（図５（ｃ））。続いて、図５（ｃ）の矢
印の方向（紙面の裏から表に向かう方向）に約１００Ｏ
ｅの磁場を印加しながら、スパタリングにより、強磁性
体層１６として約２０ｎｍ厚のＮｉＦｅ層を堆積し、続
いて、反強磁性体層１７として約２０ｎｍ厚のＦｅＭｎ
層を堆積する。Next, Al is deposited to a thickness of about 5 nm by sputtering, and an oxidation treatment is performed to form an insulator layer 1.
5 is formed (FIG. 5C). Then, about 100 O in the direction of the arrow in FIG. 5C (the direction from the back of the paper to the front).
While applying a magnetic field of e, by sputtering, a NiFe layer having a thickness of about 20 nm is deposited as the ferromagnetic material layer 16, and subsequently, as an antiferromagnetic material layer 17, a FeMn layer having a thickness of about 20 nm is deposited.
Deposit layers.
【００２９】ＦｅＭｎ層は堆積した状態で反強磁性体と
なるため、堆積後の熱処理は不要である。ＮｉＦｅ層の
磁化方向は印加磁場の方向となり、ＮｉＦｅ層の磁化方
向に影響されてＦｅＭｎ層の磁化状態が決定される。強
磁性体層１６のＮｉＦｅ層は反強磁性体層１７のＦｅＭ
ｎ層によりピンニングされる。このようにして積層構造
を形成した後、フォトリソグラフィにより約１０μｍ角
にパターニングしてトンネル接合部を形成する。Since the FeMn layer becomes an antiferromagnetic material in the deposited state, heat treatment after deposition is unnecessary. The magnetization direction of the NiFe layer is the direction of the applied magnetic field, and the magnetization state of the FeMn layer is determined by the magnetization direction of the NiFe layer. The NiFe layer of the ferromagnetic layer 16 is the FeM of the antiferromagnetic layer 17.
Pinned by the n-layer. After the laminated structure is formed in this way, it is patterned into a tunnel junction by photolithography to have a size of about 10 μm square.
【００３０】なお、反強磁性体層により強磁性体層の磁
化方向をピンニングする方法としては、上述したよう
に、反強磁性体層と強磁性体層を成膜後に磁場中で熱処
理するようにしてもよいし、磁場中で強磁性体層を成膜
し、その上に反強磁性体層を積層するようにしてもよ
い。本発明は上記実施形態に限らず種々の変形が可能で
ある。As a method of pinning the magnetization direction of the ferromagnetic layer by the antiferromagnetic layer, as described above, the antiferromagnetic layer and the ferromagnetic layer are heat-treated in a magnetic field after being formed. Alternatively, the ferromagnetic material layer may be formed in a magnetic field, and the antiferromagnetic material layer may be laminated thereon. The present invention is not limited to the above embodiment, and various modifications are possible.
【００３１】例えば、上記実施形態では、２つの強磁性
体層の磁化方向がほぼ反対向きであったが、完全に方向
が反対でなくとも、２つの強磁性体層の磁化方向が異な
っていればよい。例えば、２つの強磁性体層の磁化方向
が直交し、軟磁性体層の磁化容易軸の方向がその間にな
るようにしてもよい。また、上記実施形態では、軟磁性
体層の磁化容易軸の方向が２つの強磁性体層の方向にほ
ぼ直交していたが、軟磁性体層の磁化容易軸が他の方向
であってもよい。For example, in the above-described embodiment, the magnetization directions of the two ferromagnetic layers are substantially opposite to each other, but the two ferromagnetic layers may have different magnetization directions even if the directions are not completely opposite. Good. For example, the magnetization directions of the two ferromagnetic layers may be orthogonal to each other, and the direction of the easy axis of magnetization of the soft magnetic layer may be between them. Further, in the above embodiment, the direction of the easy axis of magnetization of the soft magnetic material layer is substantially orthogonal to the direction of the two ferromagnetic material layers, but the easy axis of magnetization of the soft magnetic material layer may be in other directions. Good.
【００３２】また、上記実施形態では、２つの強磁性体
層が共に反強磁性体層によりピンニングされていたが、
一方の強磁性体層がピンニングされていてもよい。ま
た、外部磁場により強磁性体層の磁化方向が変化しなけ
れば、ピンニングのための反強磁性体層を設けなくとも
よい。In the above embodiment, the two ferromagnetic layers are both pinned by the antiferromagnetic layer.
One of the ferromagnetic layers may be pinned. Further, if the magnetization direction of the ferromagnetic layer does not change due to the external magnetic field, the antiferromagnetic layer for pinning need not be provided.
【００３３】[0033]
【発明の効果】以上の通り、本発明によれば、磁化容易
軸の方向が異なる第１及び第２の磁性体層の間に保磁力
の小さい第３の磁性体層を設け、第１の磁性体層と３の
磁性体層の間、第２の磁性体層と第３の磁性体層の間に
絶縁体層を挿入し、第１の磁性体層と第３の磁性体層間
のトンネル抵抗と、第２の磁性体層と第３の磁性体層間
のトンネル抵抗とに基づいて外部磁界を検出するように
したので、外部磁場が印加されると、一方のトンネル抵
抗が大きく、他方のトンネル抵抗が小さくなるような相
補的な変化をするので、このような相補的に変化する抵
抗の変化の差分をとることにより、磁界検出感度を高く
すると共に、同位相で発生する雑音成分を効果的に除去
して、信号対雑音比を飛躍的に向上させることができ
る。As described above, according to the present invention, the third magnetic layer having a small coercive force is provided between the first and second magnetic layers having different directions of the easy axis of magnetization, and An insulating layer is inserted between the magnetic material layer and the third magnetic material layer, and between the second magnetic material layer and the third magnetic material layer to form a tunnel between the first magnetic material layer and the third magnetic material layer. Since the external magnetic field is detected based on the resistance and the tunnel resistance between the second magnetic layer and the third magnetic layer, when the external magnetic field is applied, one tunnel resistance is large and the other magnetic resistance is large. Since complementary changes are made such that the tunnel resistance becomes smaller, the magnetic field detection sensitivity is increased and the noise component generated in the same phase is effective by taking the difference of such complementary changes in resistance. It is possible to dramatically improve the signal-to-noise ratio.
【図１】本発明の一実施形態による磁気センサの基本構
造を示す図である。FIG. 1 is a diagram showing a basic structure of a magnetic sensor according to an embodiment of the present invention.
【図２】本発明の一実施形態による磁気センサの検出回
路の回路図である。FIG. 2 is a circuit diagram of a detection circuit of the magnetic sensor according to the embodiment of the present invention.
【図３】本発明の一実施形態の磁気センサにおける外部
磁場に対する磁気抵抗の変化を示すグラフである。FIG. 3 is a graph showing a change in magnetic resistance with respect to an external magnetic field in the magnetic sensor according to the embodiment of the present invention.
【図４】本発明の一実施形態の磁気センサにおける外部
磁場に対する再生信号出力の変化を示すグラフである。FIG. 4 is a graph showing a change in reproduction signal output with respect to an external magnetic field in the magnetic sensor according to the embodiment of the present invention.
【図５】本発明の一実施形態による磁気センサの製造方
法を示す工程図である。FIG. 5 is a process drawing showing the method of manufacturing the magnetic sensor according to the embodiment of the present invention.
１０…積層体 １１…反強磁性体層 １２…強磁性体層 １３…絶縁層 １４…軟磁性体層 １５…絶縁層 １６…強磁性体層 １７…反強磁性体層 ２０…支持基板 ＯＰ１、ＯＰ２、ＯＰ３…オペアンプ Ｒ１、Ｒ２…抵抗 DESCRIPTION OF SYMBOLS 10 ... Laminated body 11 ... Antiferromagnetic material layer 12 ... Ferromagnetic material layer 13 ... Insulating layer 14 ... Soft magnetic material layer 15 ... Insulating layer 16 ... Ferromagnetic material layer 17 ... Antiferromagnetic material layer 20 ... Support substrate OP1, OP2, OP3 ... Operational amplifier R1, R2 ... Resistor
Claims (7)
性体層と、 磁化容易軸が前記第１の方向と異なる第２の方向である
第２の磁性体層と、 前記第１の磁性体層と前記第２の磁性体層の間に位置
し、前記第１の磁性体層及び前記第２の磁性体層よりも
保磁力の小さい第３の磁性体層と、 前記第１の磁性体層と前記第３の磁性体層の間に挿入さ
れた第１の絶縁体層と、 前記第２の磁性体層と前記第３の磁性体層の間に挿入さ
れた第２の絶縁体層とを有し、 前記第１の磁性体層と前記第３の磁性体層間のトンネル
抵抗と、前記第２の磁性体層と前記第３の磁性体層間の
トンネル抵抗とに基づいて外部磁界を検出することを特
徴とする磁気センサ。1. A first magnetic layer having an easy axis of magnetization in a first direction, a second magnetic layer having an easy axis of magnetization in a second direction different from the first direction, and A third magnetic material layer located between the first magnetic material layer and the second magnetic material layer and having a coercive force smaller than that of the first magnetic material layer and the second magnetic material layer; A first insulator layer inserted between the first magnetic substance layer and the third magnetic substance layer; and a second insulator layer inserted between the second magnetic substance layer and the third magnetic substance layer. Based on a tunnel resistance between the first magnetic layer and the third magnetic layer, and a tunnel resistance between the second magnetic layer and the third magnetic layer. A magnetic sensor characterized by detecting an external magnetic field.
ることを特徴とする磁気センサ。2. The magnetic sensor according to claim 1, wherein the first direction and the second direction are substantially opposite to each other.
前記第２の方向とそれぞれほぼ直交していることを特徴
とする磁気センサ。3. The magnetic sensor according to claim 2, wherein the easy magnetization axes of the third magnetic layer are substantially orthogonal to the first direction and the second direction, respectively. Magnetic sensor.
センサにおいて、 前記第１の磁性体層と前記第２の磁性体層の少なくとも
一方の層に、磁化容易軸方向をピンニングするための反
強磁性体層を設けたことを特徴とする磁気センサ。4. The magnetic sensor according to claim 1, wherein at least one of the first magnetic body layer and the second magnetic body layer is pinned in the easy magnetization axis direction. A magnetic sensor having the antiferromagnetic material layer of 1.
センサにおいて、 前記第１の磁性体層及び前記第２の磁性体層の保磁力
が、前記第３の磁性体層の磁化困難軸方向の飽和磁場よ
りも大きいことを特徴とする磁気センサ。5. The magnetic sensor according to claim 1, wherein the coercive forces of the first magnetic layer and the second magnetic layer are difficult to magnetize in the third magnetic layer. A magnetic sensor characterized by being larger than a saturation magnetic field in the axial direction.
センサにおいて、 前記第１の磁性体層による静磁界と前記第２の磁性体層
による静磁界とが前記第３の磁性体層において互いに相
殺されていることを特徴とする磁気センサ。6. The magnetic sensor according to claim 1, wherein the static magnetic field generated by the first magnetic layer and the static magnetic field generated by the second magnetic layer are the third magnetic layer. Magnetic sensors which are offset from each other in.
センサにおいて、 前記第１の磁性体層と前記第３の磁性体層間のトンネル
抵抗に基づく第１の電気信号と、前記第２の磁性体層と
前記第３の磁性体層間のトンネル抵抗に基づく第２の電
気信号との差分を検出する差分検出手段を有することを
特徴とする磁気センサ。7. The magnetic sensor according to claim 1, wherein the first electric signal based on the tunnel resistance between the first magnetic layer and the third magnetic layer, and the second electric signal. 2. A magnetic sensor comprising: a difference detecting means for detecting a difference between the magnetic layer and the second electric signal based on the tunnel resistance between the third magnetic layer.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6220196A JPH09251618A (en) | 1996-03-19 | 1996-03-19 | Magnetic sensor |
| DE19701509A DE19701509C2 (en) | 1996-01-19 | 1997-01-17 | magnetic sensors |
| US08/785,223 US6124711A (en) | 1996-01-19 | 1997-01-17 | Magnetic sensor using tunnel resistance to detect an external magnetic field |
| FR9700469A FR2743930B1 (en) | 1996-01-19 | 1997-01-17 | MAGNETIC SENSOR FOR READING RECORDING MEDIA |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6220196A JPH09251618A (en) | 1996-03-19 | 1996-03-19 | Magnetic sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH09251618A true JPH09251618A (en) | 1997-09-22 |
Family
ID=13193307
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6220196A Pending JPH09251618A (en) | 1996-01-19 | 1996-03-19 | Magnetic sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH09251618A (en) |
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1996
- 1996-03-19 JP JP6220196A patent/JPH09251618A/en active Pending
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|---|---|---|---|---|
| US6597547B1 (en) | 1997-09-29 | 2003-07-22 | Matsushita Electric Industrial Co., Ltd. | Magnetoresistive device with an α-Fe2O3 antiferromagnetic film and indirect exchange coupling film layers of differing thickness |
| KR100302029B1 (en) * | 1997-09-29 | 2001-11-05 | 모리시타 요이찌 | Magnetoresistive element, magnetoresistive head and magnetoresistive element manufacturing method |
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| US6418001B1 (en) | 1998-12-21 | 2002-07-09 | Hitachi, Ltd. | Tunneling magnetoresistive element using a bias magnetic field |
| US6181537B1 (en) * | 1999-03-29 | 2001-01-30 | International Business Machines Corporation | Tunnel junction structure with junction layer embedded in amorphous ferromagnetic layers |
| US7345852B2 (en) | 1999-09-16 | 2008-03-18 | Kabushiki Kaisha Toshiba | Magnetoresistive element and magnetic memory device |
| US7593193B2 (en) | 1999-09-16 | 2009-09-22 | Kabushiki Kaisha Toshiba | Magnetoresistive element and magnetic memory device |
| JP2003531476A (en) * | 2000-03-22 | 2003-10-21 | モトローラ・インコーポレイテッド | Magnetic element with improved magnetoresistance ratio |
| KR20190136547A (en) * | 2018-05-31 | 2019-12-10 | 주식회사 에이엘로봇 | Printed circuit board for performoing sensing function by using wiegand effect |
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