JP3640230B2 - Thin film magnetic field sensor - Google Patents
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【０００１】
【産業上の利用分野】
本発明は、磁界感度の劣る磁気抵抗薄膜を軟磁性薄膜の高い飽和磁束密度を利用し、磁界感度を著しく向上させた磁界センサおよびこれを用いた磁気ＭＲヘッドに関するものである。
【０００２】
【従来の技術】
近年、情報の大容量化、高速化に伴い、磁気記録の分野においても更なる記録密度の高密度化が進められ、垂直磁気記録方式など様々な試みがなされている。磁気抵抗効果（ＭＲ）を利用したヘッド（ＭＲヘッド）は、上記の要請に対応するものとして注目され、現在盛んに研究されている。また、ＭＲセンサは、サーボモーターやロータリーエンコダーなどの磁界センサとしても広く利用されている。
【０００３】
このような状況の中で、従来のＭＲ材料の１０倍以上のもの巨大磁気抵抗効果（ＧＭＲ）を示す材料が、Ｆｅ／Ｃｒ系などの金属人工格子膜で見出された（Ｍ．Ｎ．Ｂａｉｂｉｃｈ ｅｔ ａｌ，Ｐｈｙｓ．Ｒｅｖ．Ｌｅｔｔ．６１（１９８８）２４７２）。ＧＭＲは、この発見をきっかけに金属人工格子のみならず、Ｍｎ酸化物などの酸化物系、Ｃｏ−Ｃｕ合金などの金属−金属系グラニュラー合金、またＣｏ−Ａｌ−Ｏ合金薄膜などの金属−非金属系グラニュラー合金薄膜などで見出され、現在盛んに研究されている。これらの材料は、ＭＲ比が大きいことから磁気ヘッドなどの磁界センサへの応用が期待されている。しかし、金属人工格子のＧＭＲを利用したスピンバルブヘッドの実用化が進められているものの、安定性や歩留まりの悪いことなど、問題は多い。また、金属人工格子以外の材料においては、磁界感度が著しく悪く、磁気ヘッドなどの磁界センサに利用することは出来なかった。
【０００４】
ＭＲ比が非常に大きいにもかかわらず、磁界感度が悪い酸化物系ＧＭＲ材料の磁界感度を向上させるユニークな方法が、Ｈ．Ｙ．Ｈｗａｎｇ等によって提案された（Ｈ．Ｙ．Ｈｗａｎｇ ｅｔ ａｌ，Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．，６８（１９９６）３４９４）。それによると、０．１ｍｍ厚のＭｎ酸化物ＧＭＲ材料を、２つの１．４７×１．４７×２４．２ｍｍ大のＭｎＺｎフェライトに挟み、フェライトの高い透磁率を利用して、見かけ上ＧＭＲの磁界感度を上げることに成功している。しかしこの報告では、フェライトの飽和磁束密度が小さいため、十分な磁界感度が得られていない上に、数ｍｍ以上の大きさのバルク材料を用いており、ＭＲヘッドなどのマイクロデバイスには用いられていない。
【０００５】
【発明が解決しようとする課題】
以上のように、薄膜ＧＭＲ材料は、その応用化が期待されているにもかかわらず、磁界感度が悪いために、ＭＲヘッドなどの磁界センサに用いることが出来なかった。特に、金属−非金属系グラニュラー合金薄膜は、成膜状態でＧＭＲを示し、また１×１０４μΩｃｍ以上の高い電気比抵抗を有し、小さな電流で大きな電圧変化が得られるなどの特長を有するにもかかわらず、磁界感度が悪いために、センサなどに用いることはできなかった。
【０００６】
本発明は、上記の事情を鑑みてなされたもので、磁界感度の悪いＧＭＲ薄膜材料を軟磁性薄膜と複合化し、磁界感度の高いＧＭＲ薄膜磁界センサを提供することを目的とする。
【０００７】
【課題を解決するための手段】
本発明は、上記の事情を鑑みて鋭意努力した結果である。磁界感度の悪いＧＭＲ薄膜材料と軟磁性薄膜を図１に示すように同一平面内に配置し、外部磁界に対する軟磁性膜の高い飽和磁束密度を利用することによって、ＧＭＲの磁界感度が著しく改善され、極めて磁界感度の高い薄膜磁界センサを得ることができる。また膜厚が数μｍ以下の薄膜材料を用い、電子ビームリソグラフィやイオンビームエッチングなどの微細加工技術を用いることによって、磁界センサのマイクロ化に対応することが可能である。
本発明の特徴とするところは次の通りである。
【０００８】
第1発明は、室温で 3 ％以上の磁気抵抗効果（ MR 比）を有する巨大磁気抵抗薄膜の 1 個の両側に、 8kG 以上の飽和磁束密度を有する軟磁性薄膜を、外部磁界により該軟磁性薄膜が磁化される位置であって、且つ該軟磁性薄膜の磁化に相当する磁界が前記巨大磁気抵抗薄膜に作用する位置に、該軟磁性薄膜の膜厚の 20 倍以下の間隔で隔てて、配置したことを特徴とする薄膜磁界センサに関する。
【０００９】
第2発明は、金属―絶縁体ナノグラニュラー構造からなり、 1 × 10 4 μΩ cm 以上の高電気比抵抗を有し、且つ室温で 3 ％以上の磁気抵抗効果（ MR 比）を有する巨大磁気抵抗薄膜の 1 個の両側に、 8kG 以上の飽和磁束密度を有する軟磁性薄膜を、外部磁界により該軟磁性薄膜が磁化される位置であって、且つ該軟磁性薄膜の磁化に相当する磁界が前記巨大磁気抵抗薄膜に作用する位置に、該軟磁性薄膜の膜厚の 20 倍以下の間隔を隔てて、配置したことを特徴とする薄膜磁界センサに関する。
【００１０】
第３発明は、同一平面内において、巨大磁気抵抗薄膜の 1 個の両側に、軟磁性薄膜を配置したことを特徴とする請求項 1 又は請求項 2 に記載の薄膜磁界センサに関する。
【００１１】
第4発明は、請求項 1 ないし請求項 3 のいずれか 1 項に記載の薄膜磁界センサからなる磁気 MR ヘッドに関する。
【００１４】
【作用】
本発明の薄膜磁界センサは、二つの軟磁性薄膜を同一平面内に膜厚の２０倍以下の隙間を隔てて配置し、その隙間にＧＭＲ薄膜を配置した構造にする必要がある。このとき、軟磁性薄膜はどちらか一方のみでも効果はあるが、上記のようにＧＭＲ薄膜を挟むように両側配置した構造とする方がより効果的である。この構造を有することによって、軟磁性薄膜が磁化すると、隙間の部分に配置されたＧＭＲ薄膜に軟磁性薄膜の磁化に相当する磁界が作用する。このため、ＧＭＲ薄膜のＭＲ比は、小さな外部磁界においてほぼ飽和値を示し、磁界感度が著しく大きくなる。
【００１５】
上記のような効果を得るためには、以下のことを考慮しなければならない。
一つは、ＧＭＲ薄膜の両側に配置される軟磁性薄膜の隙間の距離及びその形状である。隙間が広く軟磁性薄膜どうしの距離が離れすぎた場合、軟磁性薄膜から漏れる磁束が分散してしまい、ＧＭＲ薄膜に十分な磁界が作用しない。このことから、隙間の間隔は、軟磁性薄膜の膜厚の２０倍以下でなければならず、狭ければ狭いほど有効に磁界が作用する。また、膜厚方向で隙間が変化する場合、特に下部に比較して上部の隙間が大きい場合には、磁束が分散してしまい有効な磁界は作用しない。このように、隙間の形状が磁界センサの性能に大きな影響を及ぼす。軟磁性薄膜およびＧＭＲ薄膜は、ＲＦスパッタ法、イオンビームスパッタ法、あるいは蒸着法などの成膜法によって作製され、その厚さは、せいぜい数μｍかそれ以下である。そのため、本発明の磁界センサの作製にあたっては、数μｍから１μｍ以下のオーダーの加工精度が求められ、フォトレジストあるいは電子ビームリソグラフィによるリフトオフ法、またはイオンビームエッチングなどの半導体などに用いられる微細加工技術を用いる必要がある。
【００１６】
二つは、軟磁性薄膜の磁気特性である。フェライトのように飽和磁束密度が小さい場合は、弱磁界で磁化して飽和しても、その値が小さいためにＧＭＲ薄膜に、充分に有効な磁界は作用しない。このため、種々のＧＭＲ薄膜材料の飽和磁束密度を考慮すると、軟磁性薄膜の飽和磁束密度は、８ｋＧ以上であることが必要である。
【００１７】
さらにＧＭＲ薄膜の特性として、ＭＲ比が３％より小さい場合は、実用材料であるＭＲ材料のパーマロイなどと比較して、同程度かそれ以下なので、新しいＭＲセンサとしての価値がない。一方、ＧＭＲ薄膜の電気比抵抗が大きい場合には、小さな電流で大きな電圧変化が得られるために、より大きな出力が得られる。したがって、１×１０４μΩｃｍ以上の大きな電気比抵抗を有する金属−非金属ナノグラニュラー薄膜は、出力の大きな薄膜磁界センサを得るために必要である。
【００１８】
【実施例】
以下図面を参照して、本発明の実施例を詳細に説明する。
［実施例1］資料番号03の薄膜磁界センサの作製
軟磁性薄膜としてパーマロイ(Fe65Ni35)薄膜を用い、GMR薄膜に資料番号０１のCo38.6Y 14.0 O47.4ナノグラニュラー薄膜を用いて、薄膜磁界センサを作製した。パーマロイ薄膜およびCo38.6Y 14.0 O47.4ナノグラニュラー薄膜の作製にはRFスパッタ装置を用いた。図2にCo38.6Y 14.0 O47.4薄膜のMR曲線を示す。MR曲線は、磁界感度が悪くなかなか飽和にいたらない。
【００１９】
パーマロイ(Fe65Ni35)薄膜は、Fe65Ni35合金ターゲットをスパッタして作製した。膜厚は約2μmである。さらに、得られた薄膜にイオンビームエッチング装置を用いて、幅約9μmの隙間を作製した。そして、隙間の部分を残して軟磁性薄膜をマスクし、その部分に純Co円盤状にY2O3チップを配置した複合ターゲットをスパッタすることにより、図2に示したMR特性を有するCo38.6Y14.0O47.4ナノグラニュラーＧＭＲ薄膜を作製した。これによって、図1に示したようなパーマロイ(Fe65Ni35)薄膜とCo38.6Y14.0O47.4ＧＭＲ薄膜を同一平面内に配置された薄膜磁界センサが得られた。図3には、上記の薄膜磁界センサの磁界に対するMR比を示す。MR比は極めて弱い磁界において急激に変化し、その値は0.5Oeの弱磁界において約２％であり、良好な磁界感度を示している。図2に示したMR特性を有するGMR薄膜を本発明の薄膜センサに組み込むことによって、磁界感度が大幅に改善されることが分かる。
【００２０】
[実施例２]資料番号２２の薄膜磁界センサの作製
軟磁性薄膜としてFe71.3Nd9.6O19.1高電気抵抗ナノグラニュラー薄膜を用い、GMR薄膜には実施例１と同様に資料番号01のCo38.6Y 14.0 O47.4を用いて、薄膜磁界センサを作製した。Fe71.3Nd9.6O19.1薄膜およびCo38.6Y 14.0 O47.4薄膜の作製には実施例１と同様にRFスパッタ装置を用いた。
【００２１】
Fe71.3Nd9.6O19.1薄膜は、純Co円板状にNd2O3チップを配置した複合ターゲットをスパッタすることにより作製した。膜厚は約2μｍである。その他の作製法は実施例１と同様である。図4には、上記の薄膜磁界センサの磁界に対するMR比を示す。MR比は極めて弱い磁界において急激に変化し、その値は1Oeの弱磁界において約2.1％であり、良好な磁界感度を示している。
【００２２】
表１には、本発明の薄膜磁界センサにおいて、様々な軟磁性薄膜とＧＭＲ薄膜を組み合わせた場合の１ＯｅにおけるＭＲ比を示した。表に見られるように、ＧＭＲ薄膜が単独な場合（比較例）より、本発明の薄膜磁界センサのＭＲ比の方が著しく向上していることが判る。
【００２３】
【表１】
表１に示した軟磁性薄膜はいずれも８ｋＧ以上の飽和磁束密度を有し、ＧＭＲ薄膜は１０ＫＯｅで３％以上のＭＲ比と１×１０4μΩｃｍ以上の電気比抵抗を有する。表１に示されたいずれのセンサも弱磁界で大きなＭＲ比を有し、大きな磁界感度を示す。
【００２５】
上記の通り、本発明の薄膜磁界センサは、ＭＲ比の磁界感度が優れているので、磁気ＭＲヘッドにも好適である。
【００２６】
【発明の効果】
本発明の薄膜磁界センサは、軟磁性薄膜とＧＭＲ薄膜とから構成することにより、ＧＭＲの磁界感度が著しく向上する。ＧＭＲ材料を用いることによって、現在使用されているパーマロイなどを使用したＭＲ磁界センサに比べて大きな出力が得られ、また薄膜材料と微細加工技術を用いているので、磁界センサ素子のマイクロ化にも対応することができ、その工業的意義は大きく、磁気ＭＲヘッドなどにも好適である。
【図面の簡単な説明】
【図１】本発明の薄膜磁界センサの構造を示す斜視図である。
【図２】 Co38.6Y 14.0 O47.4ナノグラニュラーGMR薄膜の磁界とMR比の関係を示す特性図である。
【図３】軟磁性薄膜にFe65Ni35薄膜、GMR薄膜にCo38.6Y 14.0 O47.4ナノグラニュラー薄膜を用いた場合の本発明センサの磁界とMR比の関係を示す特性図である。
【図４】軟磁性薄膜にFe71.3Nd9.6O19.1高電気抵抗ナノグラニュラー薄膜、GMR薄膜にCo38.6Y 14.0 O47.4ナノグラニュラー薄膜を用いた場合の本発明センサの磁界とMR比の関係を示す特性図である。[0001]
[Industrial application fields]
The present invention relates to a magnetic field sensor in which a magnetoresistive thin film having inferior magnetic field sensitivity is utilized by utilizing a high saturation magnetic flux density of a soft magnetic thin film, and the magnetic field sensitivity is remarkably improved, and a magnetic MR head using the same.
[0002]
[Prior art]
In recent years, with the increase in capacity and speed of information, the recording density has been further increased in the field of magnetic recording, and various attempts such as perpendicular magnetic recording have been made. A head (MR head) using the magnetoresistive effect (MR) has been attracting attention as a response to the above-described demand, and is being actively studied. MR sensors are also widely used as magnetic field sensors such as servo motors and rotary encoders.
[0003]
Under such circumstances, a material exhibiting a giant magnetoresistive effect (GMR) more than 10 times that of a conventional MR material has been found in a metal artificial lattice film such as Fe / Cr (MN). Baibich et al, Phys. Rev. Lett. 61 (1988) 2472). With this discovery, GMR is not only a metal artificial lattice, but also oxides such as Mn oxides, metal-metal granular alloys such as Co-Cu alloys, and metal-non-metals such as Co-Al-O alloy thin films. Found in metallic granular alloy thin films, etc., it is being actively researched. Since these materials have a large MR ratio, they are expected to be applied to magnetic field sensors such as magnetic heads. However, although a spin valve head using a metal artificial lattice GMR has been put into practical use, there are many problems such as poor stability and yield. Further, materials other than the artificial metal lattice have extremely poor magnetic field sensitivity, and cannot be used for magnetic field sensors such as magnetic heads.
[0004]
A unique method for improving the magnetic field sensitivity of oxide-based GMR materials with poor magnetic field sensitivity despite a very high MR ratio is described in H.W. Y. Proposed by Hwang et al. (H. Y. Hwang et al, Appl. Phys. Lett., 68 (1996) 3494). According to it, a 0.1 mm thick Mn oxide GMR material is sandwiched between two 1.47 × 1.47 × 24.2 mm MnZn ferrites, and apparently GMR's It has succeeded in increasing the magnetic field sensitivity. However, in this report, since the saturation magnetic flux density of ferrite is small, sufficient magnetic field sensitivity is not obtained, and a bulk material with a size of several millimeters or more is used, and it is used for micro devices such as MR heads. Not.
[0005]
[Problems to be solved by the invention]
As described above, although the thin film GMR material is expected to be applied, it cannot be used for a magnetic field sensor such as an MR head due to poor magnetic field sensitivity. In particular, the metal-nonmetallic granular alloy thin film exhibits GMR in a film formation state, has a high electrical resistivity of 1 × 10 4 μΩcm or more, and has a feature such that a large voltage change can be obtained with a small current. Nevertheless, due to poor magnetic field sensitivity, it could not be used for sensors.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a GMR thin film magnetic field sensor having high magnetic field sensitivity by combining a GMR thin film material having poor magnetic field sensitivity with a soft magnetic thin film.
[0007]
[Means for Solving the Problems]
The present invention is the result of diligent efforts in view of the above circumstances. By arranging the GMR thin film material and the soft magnetic thin film having poor magnetic field sensitivity in the same plane as shown in FIG. 1 and utilizing the high saturation magnetic flux density of the soft magnetic film with respect to the external magnetic field, the magnetic field sensitivity of the GMR is remarkably improved. A thin film magnetic field sensor with extremely high magnetic field sensitivity can be obtained. Further, by using a thin film material having a film thickness of several μm or less and using a microfabrication technique such as electron beam lithography or ion beam etching, it is possible to cope with the miniaturization of the magnetic field sensor.
The features of the present invention are as follows.
[0008]
The first invention, one either side of the giant magnetoresistive thin film having a room temperature for 3% or more of the magnetoresistive (MR ratio), a soft magnetic thin film having a saturation magnetic flux density of more than 8 kg, soft magnetic by an external magnetic field At a position where the thin film is magnetized, and at a position where a magnetic field corresponding to the magnetization of the soft magnetic thin film acts on the giant magnetoresistive thin film , separated by an interval of 20 times or less the thickness of the soft magnetic thin film , The present invention relates to a thin film magnetic field sensor characterized by being arranged .
[0009]
The second invention is a metal - an insulating body nano-granular structure, 1 × 10 4 has a [mu] [Omega] cm or more high electrical resistivity, and at room temperature for giant magnetoresistive thin film having more than 3% of the magnetoresistive (MR ratio) of the one sides, the soft magnetic thin film having a saturation magnetic flux density of more than 8 kg, a position where the soft magnetic thin film is magnetized by an external magnetic field, and giant corresponding magnetic field the magnetization of the soft magnetic thin film The present invention relates to a thin film magnetic field sensor that is disposed at a position acting on a magnetoresistive thin film at an interval of 20 times or less the film thickness of the soft magnetic thin film .
[0010]
A third invention relates to the thin film magnetic field sensor according to
[0011]
The fourth invention relates to a magnetic MR head formed of a thin film magnetic sensor according to any one of
[0014]
[Action]
The thin film magnetic field sensor of the present invention needs to have a structure in which two soft magnetic thin films are arranged in the same plane with a gap of 20 times or less of the film thickness and a GMR thin film is arranged in the gap. At this time, although only one of the soft magnetic thin films is effective, it is more effective to have a structure in which both sides are disposed so as to sandwich the GMR thin film as described above. With this structure, when the soft magnetic thin film is magnetized, a magnetic field corresponding to the magnetization of the soft magnetic thin film acts on the GMR thin film disposed in the gap. For this reason, the MR ratio of the GMR thin film exhibits a substantially saturated value in a small external magnetic field, and the magnetic field sensitivity is remarkably increased.
[0015]
In order to obtain the above effects, the following must be considered.
One is the distance and the shape of the gap between the soft magnetic thin films disposed on both sides of the GMR thin film. When the gap is wide and the distances between the soft magnetic thin films are too large, the magnetic flux leaking from the soft magnetic thin film is dispersed, and a sufficient magnetic field does not act on the GMR thin film. For this reason, the gap must be 20 times or less the thickness of the soft magnetic thin film, and the narrower the magnetic field acts more effectively. Further, when the gap changes in the film thickness direction, especially when the upper gap is larger than the lower part, the magnetic flux is dispersed and an effective magnetic field does not act. As described above, the shape of the gap greatly affects the performance of the magnetic field sensor. The soft magnetic thin film and the GMR thin film are produced by a film forming method such as an RF sputtering method, an ion beam sputtering method, or an evaporation method, and the thickness is at most several μm or less. Therefore, in manufacturing the magnetic field sensor of the present invention, processing accuracy on the order of several μm to 1 μm or less is required, and a fine processing technique used for semiconductors such as a lift-off method by photoresist or electron beam lithography or ion beam etching. Must be used.
[0016]
Two are the magnetic properties of soft magnetic thin films. When the saturation magnetic flux density is small like ferrite, even if it is magnetized and saturated with a weak magnetic field, the value is small, so that a sufficiently effective magnetic field does not act on the GMR thin film. For this reason, considering the saturation magnetic flux density of various GMR thin film materials, the saturation magnetic flux density of the soft magnetic thin film needs to be 8 kG or more.
[0017]
Further, as the characteristics of the GMR thin film, when the MR ratio is smaller than 3%, it is not equivalent to a new MR sensor because it is comparable or lower than the permalloy of MR material which is a practical material. On the other hand, when the electrical specific resistance of the GMR thin film is large, a large voltage change can be obtained with a small current, so that a larger output can be obtained. Therefore, a metal-nonmetal nanogranular thin film having a large electrical resistivity of 1 × 10 4 μΩcm or more is necessary to obtain a thin film magnetic field sensor having a large output.
[0018]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[Example 1] Fabrication of thin film magnetic field sensor of material number 03 Permalloy (Fe 65 Ni 35 ) thin film was used as a soft magnetic thin film, and Co 38.6 Y 14.0 O 47.4 nano granular thin film of material number 01 was used as a GMR thin film. A sensor was fabricated. An RF sputtering apparatus was used to fabricate permalloy thin films and Co 38.6 Y 14.0 O 47.4 nanogranular thin films. FIG. 2 shows the MR curve of the Co 38.6 Y 14.0 O 47.4 thin film. The MR curve does not easily reach saturation due to poor magnetic field sensitivity.
[0019]
The permalloy (Fe 65 Ni 35 ) thin film was prepared by sputtering an Fe 65 Ni 35 alloy target. The film thickness is about 2 μm. Further, a gap having a width of about 9 μm was formed on the obtained thin film using an ion beam etching apparatus. Then, by masking the soft magnetic thin film leaving a gap, and sputtering a composite target in which Y 2 O 3 chips are arranged in a pure Co disk shape on the part, Co 38.6 having the MR characteristics shown in FIG. A Y 14.0 O 47.4 nanogranular GMR thin film was prepared. As a result, a thin film magnetic field sensor in which a permalloy (Fe 65 Ni 35 ) thin film and a Co 38.6 Y 14.0 O 47.4 GMR thin film as shown in FIG. 1 were arranged in the same plane was obtained. FIG. 3 shows the MR ratio of the thin film magnetic field sensor to the magnetic field. The MR ratio changes abruptly in a very weak magnetic field, and the value is about 2% in a weak magnetic field of 0.5 Oe, indicating a good magnetic field sensitivity. It can be seen that the magnetic field sensitivity is significantly improved by incorporating the GMR thin film having the MR characteristics shown in FIG. 2 into the thin film sensor of the present invention.
[0020]
[Example 2] Fabrication of thin film magnetic field sensor of Document No. 22 Fe 71.3 Nd 9.6 O 19.1 High electrical resistance nano granular thin film was used as the soft magnetic thin film, and Co 38.6 Y 14.0 of Document No. 01 was used for the GMR thin film as in Example 1. A thin film magnetic field sensor was fabricated using O 47.4 . An RF sputtering apparatus was used in the same manner as in Example 1 for producing the Fe 71.3 Nd 9.6 O 19.1 thin film and the Co 38.6 Y 14.0 O 47.4 thin film.
[0021]
The Fe 71.3 Nd 9.6 O 19.1 thin film was fabricated by sputtering a composite target in which Nd 2 O 3 chips were arranged in a pure Co disk shape. The film thickness is about 2 μm. Other manufacturing methods are the same as those in Example 1. FIG. 4 shows the MR ratio of the thin film magnetic field sensor to the magnetic field. The MR ratio changes abruptly in an extremely weak magnetic field, and the value is about 2.1% in a weak magnetic field of 1 Oe, indicating a good magnetic field sensitivity.
[0022]
Table 1 shows MR ratios at 1 Oe when various soft magnetic thin films and GMR thin films are combined in the thin film magnetic field sensor of the present invention. As can be seen from the table, the MR ratio of the thin film magnetic field sensor of the present invention is remarkably improved as compared with the case where the GMR thin film is used alone (comparative example).
[0023]
[Table 1]
All of the soft magnetic thin films shown in Table 1 have a saturation magnetic flux density of 8 kG or more, and the GMR thin film has an MR ratio of 3% or more and an electrical resistivity of 1 × 10 4 μΩcm or more at 10 KOe. All the sensors shown in Table 1 have a large MR ratio in a weak magnetic field, and exhibit a large magnetic field sensitivity.
[0025]
As described above, the thin film magnetic field sensor of the present invention is excellent in the magnetic field sensitivity of the MR ratio, and is therefore suitable for a magnetic MR head.
[0026]
【The invention's effect】
The thin film magnetic field sensor of the present invention is composed of a soft magnetic thin film and a GMR thin film, thereby significantly improving the magnetic field sensitivity of GMR. By using GMR material, a large output can be obtained compared to the MR magnetic field sensor using permalloy currently used, and since the thin film material and the fine processing technology are used, the magnetic field sensor element can be miniaturized. The industrial significance is great, and it is suitable for a magnetic MR head.
[Brief description of the drawings]
FIG. 1 is a perspective view showing the structure of a thin film magnetic field sensor of the present invention.
FIG. 2 is a characteristic diagram showing the relationship between the magnetic field and MR ratio of Co 38.6 Y 14.0 O 47.4 nanogranular GMR thin film.
FIG. 3 is a characteristic diagram showing the relationship between the magnetic field and MR ratio of the sensor of the present invention when Fe 65 Ni 35 thin film is used as the soft magnetic thin film and Co 38.6 Y 14.0 O 47.4 nano granular thin film is used as the GMR thin film.
FIG. 4 is a characteristic diagram showing the relationship between the magnetic field and MR ratio of the sensor of the present invention when Fe 71.3 Nd 9.6 O 19.1 high electrical resistance nano granular thin film is used for soft magnetic thin film and Co 38.6 Y 14.0 O 47.4 nano granular thin film is used for GMR thin film. It is.
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27930897A JP3640230B2 (en) | 1997-09-04 | 1997-09-04 | Thin film magnetic field sensor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27930897A JP3640230B2 (en) | 1997-09-04 | 1997-09-04 | Thin film magnetic field sensor |
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| JPH1187804A JPH1187804A (en) | 1999-03-30 |
| JP3640230B2 true JP3640230B2 (en) | 2005-04-20 |
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| JP27930897A Expired - Lifetime JP3640230B2 (en) | 1997-09-04 | 1997-09-04 | Thin film magnetic field sensor |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| DE60139017D1 (en) * | 2000-10-26 | 2009-07-30 | Foundation The Res Inst Of Ele | THIN FILM MAGNETIC SENSOR |
| JP2004363157A (en) * | 2003-06-02 | 2004-12-24 | Res Inst Electric Magnetic Alloys | Thin film magnetic sensor and its manufacturing method |
| JP4953569B2 (en) * | 2004-11-29 | 2012-06-13 | 公益財団法人電磁材料研究所 | Thin film magnetoresistive element and magnetic sensor using thin film magnetoresistive element |
| JP4520353B2 (en) * | 2005-04-15 | 2010-08-04 | 大同特殊鋼株式会社 | Thin film magnetic sensor |
| JP2007073644A (en) * | 2005-09-05 | 2007-03-22 | Osaka Industrial Promotion Organization | Magnetoresistive element and its manufacturing method |
| JP5151551B2 (en) | 2008-02-27 | 2013-02-27 | 大同特殊鋼株式会社 | Thin film magnetic sensor |
| JP2018096895A (en) | 2016-12-15 | 2018-06-21 | Tdk株式会社 | Magnetic field detection device |
| JP6777058B2 (en) | 2017-11-09 | 2020-10-28 | Tdk株式会社 | Magnetic sensor |
| JP2019087688A (en) | 2017-11-09 | 2019-06-06 | Tdk株式会社 | Magnetic sensor |
| JP6828676B2 (en) | 2017-12-27 | 2021-02-10 | Tdk株式会社 | Magnetic sensor |
| JP6605570B2 (en) | 2017-12-27 | 2019-11-13 | Ｔｄｋ株式会社 | Magnetic sensor |
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