JP2742691B2 - Superconducting magnetic sensor - Google Patents
Superconducting magnetic sensorInfo
- Publication number
- JP2742691B2 JP2742691B2 JP63235484A JP23548488A JP2742691B2 JP 2742691 B2 JP2742691 B2 JP 2742691B2 JP 63235484 A JP63235484 A JP 63235484A JP 23548488 A JP23548488 A JP 23548488A JP 2742691 B2 JP2742691 B2 JP 2742691B2
- Authority
- JP
- Japan
- Prior art keywords
- superconductor
- magnetic sensor
- magnetic field
- solenoid coil
- sensitivity
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Description
【発明の詳細な説明】 『発明の利用分野』 本発明は粒界を有する超伝導体を用いた磁気センサー
に関する。本発明は全く新しいタイプの磁気センサーに
関するものであり、さらに本発明ではこの磁気センサー
をより高感度なものとする方法について述べる。本発明
による高感度でかつ構造が簡単で安価な磁気センサーは
学術上も工業上も有益なものであり、様々な分野で利用
されることが期待される。The present invention relates to a magnetic sensor using a superconductor having a grain boundary. The present invention relates to a completely new type of magnetic sensor, and the present invention describes a method for making this magnetic sensor more sensitive. The magnetic sensor having high sensitivity, simple structure, and low cost according to the present invention is useful scientifically and industrially, and is expected to be used in various fields.
『従来の技術』 従来より高感度磁気センサーとしては量子干渉型磁気
センサー、いわゆるSQUIDが知られている。この従来の
磁気センサーの感度は非常に高いが、構造が複雑で、価
格・維持費が高くつくという欠点があった。[Prior Art] Conventionally, a quantum interference magnetic sensor, so-called SQUID, has been known as a high-sensitivity magnetic sensor. Although the sensitivity of this conventional magnetic sensor is very high, it has the drawback that the structure is complicated and the cost and maintenance cost are high.
一方、感度はそれほど要求されないが、手軽に使え
て、価格も安いというタイプの磁気センサーの需要もあ
った。そのような要求を満たす磁気センサーとしては半
導体磁気センサーがあったが、その感度は50〔Oe〕（エ
ールステッド）程度であり、これより多少感度の高い１
〔Oe〕以下の検出感度をもつ磁気センサーの登場が待ち
望まれていた。On the other hand, there was a demand for a magnetic sensor of a type that does not require much sensitivity but is easy to use and inexpensive. As a magnetic sensor that satisfies such demands, there is a semiconductor magnetic sensor, but its sensitivity is about 50 [Oe] (Oersted), which is slightly higher than this.
[Oe] The emergence of a magnetic sensor having the following detection sensitivity has been awaited.
近年、酸化物超伝導体YBCOやBSCCOが発見され、その
物性を調査するうえで、微小な磁場によって、Tcもしく
は臨界電流値が著しく低下するという現象が報告されて
いる。In recent years, oxide superconductors YBCO and BSCCO have been discovered, and in investigating their physical properties, it has been reported that a small magnetic field significantly reduces Tc or critical current value.
この現象は、超伝導体の粒界がジョセフソン接合とな
って作用する為である。This phenomenon is because the grain boundary of the superconductor acts as a Josephson junction.
本発明はこの性質を利用して超伝導体を磁気センサー
として使用するものであります。The present invention utilizes this property to use superconductors as magnetic sensors.
すなわち、超伝導体に臨界電流よりやや少ない電流を
流しておき（この状態では超伝導体に電圧は生じていな
い）、この超伝導体に微少な磁場をかけると超伝導状態
が一部破れて、電圧が生じる。発生する電圧と磁場との
間には第１図に示すような１対１の対応関係があるため
電圧を読み取れば磁場の大きさがわかる。しかしなが
ら、このような磁気センサーでは同じ材料で作製しても
作製条件によって特性が異なるため、信頼性に乏しい。That is, a current slightly lower than the critical current is passed through the superconductor (in this state, no voltage is generated in the superconductor), and when a small magnetic field is applied to the superconductor, the superconducting state is partially broken. , Voltage occurs. Since there is a one-to-one correspondence between the generated voltage and the magnetic field as shown in FIG. 1, the magnitude of the magnetic field can be determined by reading the voltage. However, such a magnetic sensor has poor reliability because its characteristics are different depending on the manufacturing conditions even if it is made of the same material.
そこで本発明者は、この磁気センサーを発展させ、よ
り高感度で信頼性が高く工業的な応用も簡単な磁気セン
サーを提供するものである。Therefore, the present inventor has developed this magnetic sensor to provide a magnetic sensor with higher sensitivity, higher reliability and simple industrial application.
以下にその構造と動作を第２図に従って示す。第２図
はその概念図である。４つの電極、すなわち、通常の抵
抗率を測定する際に取りつけるのと同じように、電流供
給電極と電圧測定電極がそれぞれ２つずつが取りつけら
れた超伝導体（１）がソレノイドコイル（２）の中にあ
るという構造になっている。ソレノイドコイル（２）は
極めて正確にその磁場を制御できるものであり、その内
部の磁場は均一である。超伝導体には安定化電源（３）
によって電流I1が流されている。ソレノイドコイル
（２）には交流電源（周波数は数Hzから数十Hz）（４）
によって電流I2が流される。外部からは図の左から定常
磁場Ｈがかけられている。The structure and operation will be described below with reference to FIG. FIG. 2 is a conceptual diagram. A superconductor (1) having two current supply electrodes and two voltage measurement electrodes attached to each other is a solenoid coil (2) in the same manner as the four electrodes are attached when measuring a normal resistivity. It has a structure that is inside. The solenoid coil (2) can control its magnetic field very accurately, and the magnetic field inside is uniform. Stabilized power supply for superconductor (3)
Current I 1 is flown by. AC power (frequency is several Hz to several tens of Hz) for solenoid coil (2) (4)
It flows a current I 2 by. A stationary magnetic field H is applied from the outside from the left in the figure.
ソレノイドコイル（２）の発生する１周期の最大磁場
の大きさは、磁場Ｈよりも大きいとする。交流電源
（４）によってソレノイドコイル（２）の発生する磁場
の大きさと向きは周期的に変化し、磁場Ｈとの合成によ
ってソレノイドコイル（２）の内部の磁場の大きさは周
期的にゼロになったり、ゼロでなくなったりする。この
とき、オシロスコープ（５）を用いて、ソレノイドコイ
ル（２）に流れる電流を横軸に、超伝導体（１）に生ず
る電圧を縦軸にとると、超伝導隊（１）に流す電流値I1
の値に依って、第３図のようなスペクトルが得られる。It is assumed that the magnitude of the maximum magnetic field of one cycle generated by the solenoid coil (2) is larger than the magnetic field H. The magnitude and direction of the magnetic field generated by the solenoid coil (2) are periodically changed by the AC power supply (4), and the magnitude of the magnetic field inside the solenoid coil (2) is periodically reduced to zero by combination with the magnetic field H. Or zero. At this time, when the current flowing through the solenoid coil (2) is plotted on the horizontal axis and the voltage generated in the superconductor (1) is plotted on the vertical axis using the oscilloscope (5), the current value flowing through the superconducting corps (1) I 1
A spectrum as shown in FIG. 3 is obtained depending on the value of.
第３図には３種類のスペクトルが描かれているが、
（ａ）は電流I1が小さいとき、（ｂ）は丁度よいとき、
（ｃ）は大きすぎるときである。FIG. 3 shows three types of spectra.
(A) when the current I 1 is small, (b) when just right,
(C) is when it is too large.
これらのスペクトルは、ソレノイドコイル（２）に流
れる電流I2がI0のとき、ソレノイドコイル（２）内の磁
場がゼロになり、超伝導体（１）の電圧がゼロ、あるい
は電圧が極小値を取り、それ以外のときには磁場電圧効
果によって電圧が生じている状態を示している。（ｂ）
のスペクトルにおける半値幅ｗがこの磁気センサーの分
解能である。These spectra show that when the current I 2 flowing through the solenoid coil (2) is I 0 , the magnetic field in the solenoid coil (2) becomes zero, and the voltage of the superconductor (1) becomes zero or the voltage becomes a minimum value. In other cases, a voltage is generated due to the magnetic field voltage effect. (B)
Is the resolution of this magnetic sensor.
これはソレノイドコイル（２）が十分精密に作られて
いるならば、超伝導体（１）によって決定される。実
際、コイルは極めて精密に作ることができるので、超伝
導体（１）の持つ特性が磁気センサーの特性を左右する
ことになる。This is determined by the superconductor (1) if the solenoid coil (2) is made sufficiently precise. In fact, the coil can be made very precisely, so that the properties of the superconductor (1) will determine the properties of the magnetic sensor.
粒界がジョセフソン接合の役割をする超伝導体におい
てこの超伝導体が反応する最小磁場H0は で与えられる。ここでφ０は磁束量子で2.07×10-7Ocem
2、λは超伝導体の磁場浸入長、Ｌは接合部の長さの代
表的な大きさである。このH0が上記スペクトルの半値幅
ｗとなる。Minimum field H 0 to the superconductor will react in superconductor grain boundaries serve Josephson junction Given by Where φ 0 is 2.07 × 10 -7 Ocem
2 , λ is the length of magnetic field penetration of the superconductor, and L is a typical length of the junction. This H 0 is the half width w of the spectrum.
したがって、磁気センサーの感度を上げるためには、
λかＬかを大きくすればよい。λは物質によって決まっ
ているからλの大きな材料、すなわち下部臨界磁場の小
さな材料を使うと感度をあげることができる。Therefore, to increase the sensitivity of the magnetic sensor,
It is sufficient to increase λ or L. Since λ is determined by the substance, sensitivity can be increased by using a material having a large λ, that is, a material having a small lower critical magnetic field.
さらに超伝導転移温度近傍ではλは大きくなるから、
磁気センサーを超伝導転移温度近傍で使用すると感度を
上げることができる。Furthermore, since λ increases near the superconducting transition temperature,
Using a magnetic sensor near the superconducting transition temperature can increase sensitivity.
Ｌについては、セラミックスの場合、Ｌは粒径と考え
られるので、粒径の大きな材料を使用すると感度があが
る。Regarding L, in the case of ceramics, since L is considered to be the particle size, the sensitivity is increased by using a material having a large particle size.
以上のような工夫をした結果、0.1〔Oe〕の検出感度
を達成することができた。以下に実施例を示し、さらに
詳しく本発明を説明する。As a result of the above contrivance, a detection sensitivity of 0.1 [Oe] was able to be achieved. Hereinafter, the present invention will be described in more detail with reference to Examples.
『実施例』 超伝導体はYBCOに不純物としてニッケルをくわえたも
のを用いた。ニッケルは超伝導転移温度を下げる作用を
する。[Example] A superconductor obtained by adding nickel as an impurity to YBCO was used. Nickel acts to lower the superconducting transition temperature.
本実施例では磁気センサーを液体窒素温度で使用する
ので、前述のように、超伝導転移温度を液体窒素温度に
近づけるためにニッケルを加えた。これにより、磁気セ
ンサーの感度を向上させることが可能となった。In this embodiment, since the magnetic sensor is used at the temperature of liquid nitrogen, nickel was added to bring the superconducting transition temperature close to the temperature of liquid nitrogen as described above. This has made it possible to improve the sensitivity of the magnetic sensor.
本実施例における超伝導酸化物の作製には通常の固相
反応を用いた。原料としては、酸化イットリウム、炭化
バリウム、酸化銅、酸化ニッケルの粉末（純度は全て3
N）を用いた。A normal solid-state reaction was used for producing the superconducting oxide in this example. Raw materials include yttrium oxide, barium carbide, copper oxide, and nickel oxide powder (purity is 3
N) was used.
原料中のイットリウム、バリウム、銅、ニッケルの比
を1:2:3.9:0.1としてよく混合し、大気中で900℃、12時
間仮焼成した後、10×１×0.7mm3の直方体に成形し、再
び、大気中で900℃、12時間焼成したのち、毎分１℃の
速度で冷却した。Yttrium in the raw material, barium, copper, a ratio of nickel 1: 2: 3.9 were mixed well as a 0.1, 900 ° C. in air, after calcination for 12 hours, and molded into a rectangular parallelepiped of 10 × 1 × 0.7 mm 3 After calcining again in the air at 900 ° C. for 12 hours, it was cooled at a rate of 1 ° C. per minute.
銅を化学量論比より多く加えたのは粒径を大きくして
感度を増すためである。このようにして作製された超伝
導体のTc（ゼロ抵抗温度）は79Kである。この超伝導材
料に電極を付け、第２図のようにソレノイドコイル
（２）の中に置いた。Copper was added in excess of the stoichiometric ratio in order to increase the particle size and increase sensitivity. The Tc (zero resistance temperature) of the superconductor thus manufactured is 79K. An electrode was attached to this superconducting material and placed in a solenoid coil (2) as shown in FIG.
この磁気センサー装置を液体窒素中に置き、超伝導体
（１）には50mAの電流を流した。この時にソレノイドコ
イル（２）に流れる電流と超伝導体（１）に生じる電圧
の関係は第３図に示されている。コイルに流れる電流1m
Aの時、コイルに生じる磁場は0.5〔Oe〕であった。This magnetic sensor device was placed in liquid nitrogen, and a current of 50 mA was passed through the superconductor (1). At this time, the relationship between the current flowing through the solenoid coil (2) and the voltage generated in the superconductor (1) is shown in FIG. 1m current flowing through coil
At the time of A, the magnetic field generated in the coil was 0.5 [Oe].
またI0は2.2mAであったので、このソレノイドコイル
（２）により発生する磁場に等しい、外部磁場Ｈの大き
さは1.1〔Oe〕であり、磁気センサーの検出感度は0.1
〔Oe〕であった。Since I 0 was 2.2 mA, the magnitude of the external magnetic field H, which is equal to the magnetic field generated by the solenoid coil (2), was 1.1 [Oe], and the detection sensitivity of the magnetic sensor was 0.1
[Oe].
本実施例では超伝導体として酸化物超伝導体を用いた
が他の超伝導体においても同様に適用することが可能で
ある。In this embodiment, an oxide superconductor is used as the superconductor, but the same can be applied to other superconductors.
『効果』 本発明では超伝導体の作製条件、種類に関係なく、粒
界を有する超伝導体であるなら全ての超伝導体によっ
て、同じ磁場の絶対値が得られる。[Effect] In the present invention, the same absolute value of the magnetic field can be obtained by all superconductors as long as they are superconductors having grain boundaries, regardless of the production conditions and types of superconductors.
すなわち、超伝導体の作製条件、種類による、特性曲
線等を作製しなくてもよい。ただし検出感度は作製条
件、種類に依存するが、これは一定の基準を超えればよ
く、量産にあたって何ら問題とならない。本発明によっ
てローコストで高感度な磁気センサーが作成できるよう
になった。このことによる工業上の利益は莫大なもので
ある。本発明においては、超伝導体が板状であっても、
薄膜状であってもその動作原理は変わらない。実施例に
は述べなかったが、超伝導体を適当な基板上に薄膜とし
て形成しその断面積を小さくすることによって、より高
感度な磁気センサーを作成することが可能である。That is, it is not necessary to produce a characteristic curve or the like depending on the production conditions and types of the superconductor. However, the detection sensitivity depends on the production conditions and types, but this may only exceed a certain standard, and does not pose any problem in mass production. According to the present invention, a low-cost, high-sensitivity magnetic sensor can be manufactured. The industrial benefits from this are enormous. In the present invention, even if the superconductor is plate-shaped,
Even if it is in the form of a thin film, its operating principle does not change. Although not described in the embodiments, it is possible to produce a magnetic sensor with higher sensitivity by forming a superconductor as a thin film on an appropriate substrate and reducing its cross-sectional area.
第１図は粒界を有する超伝導体の磁気電圧効果の例を示
す。 横軸：印加磁場 縦軸：超伝導体に生じる電圧 第２図は磁気センサーの概念図を示す。 第３図は本発明の磁気センサーの特性の一例を示す。 横軸：ソレノイドコイルに流れる電流 縦軸：超伝導体に生じる電圧 （ａ）I1＝10mA （ｂ）I1＝50mA （ｃ）I1＝200mA １……超伝導体 ２……ソレノイドコイルFIG. 1 shows an example of the magneto-voltage effect of a superconductor having a grain boundary. Horizontal axis: applied magnetic field Vertical axis: voltage generated in the superconductor FIG. 2 shows a conceptual diagram of the magnetic sensor. FIG. 3 shows an example of the characteristics of the magnetic sensor of the present invention. Horizontal axis: current vertical axis through the solenoid coil: superconductor occurring voltage (a) I 1 = 10mA ( b) I 1 = 50mA (c) I 1 = 200mA 1 ...... superconductor 2 ...... solenoid coil
Claims (2)
せる手段と、 前記ソレノイドコイル中におかれた超伝導体と、 前記超伝導体に定電流を流す手段と、 前記超伝導体に発生する電圧を測定する手段と を有することを特徴とする超電導磁気センサー。1. A solenoid coil, means for supplying an alternating current to the solenoid coil to generate a magnetic field, a superconductor placed in the solenoid coil, means for supplying a constant current to the superconductor, Means for measuring a voltage generated in the superconductor.
超伝導体は磁気センサーの使用温度近傍に超伝導転移温
度を有することを特徴とする超伝導磁気センサー。2. The superconducting magnetic sensor according to claim 1, wherein the superconductor has a superconducting transition temperature near the operating temperature of the magnetic sensor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63235484A JP2742691B2 (en) | 1988-09-19 | 1988-09-19 | Superconducting magnetic sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63235484A JP2742691B2 (en) | 1988-09-19 | 1988-09-19 | Superconducting magnetic sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0282178A JPH0282178A (en) | 1990-03-22 |
| JP2742691B2 true JP2742691B2 (en) | 1998-04-22 |
Family
ID=16986744
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63235484A Expired - Lifetime JP2742691B2 (en) | 1988-09-19 | 1988-09-19 | Superconducting magnetic sensor |
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| Country | Link |
|---|---|
| JP (1) | JP2742691B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5254945A (en) * | 1989-06-30 | 1993-10-19 | Sharp Kabushiki Kaisha | Magneto-resistive superconductive device and method for sensing magnetic fields |
| CN109490798B (en) * | 2018-09-26 | 2020-02-21 | 上海交通大学 | High-temperature superconducting coil magnetic field measurement method based on optical fiber magnetic field sensing technology |
Family Cites Families (1)
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|---|---|---|---|---|
| JPH0671100B2 (en) * | 1987-07-29 | 1994-09-07 | シャープ株式会社 | Superconducting magnetoresistive device |
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1988
- 1988-09-19 JP JP63235484A patent/JP2742691B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0282178A (en) | 1990-03-22 |
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