JP2501629B2 - Superconducting weak junction - Google Patents
Superconducting weak junctionInfo
- Publication number
- JP2501629B2 JP2501629B2 JP63249427A JP24942788A JP2501629B2 JP 2501629 B2 JP2501629 B2 JP 2501629B2 JP 63249427 A JP63249427 A JP 63249427A JP 24942788 A JP24942788 A JP 24942788A JP 2501629 B2 JP2501629 B2 JP 2501629B2
- Authority
- JP
- Japan
- Prior art keywords
- superconductor
- superconducting
- layer
- complex oxide
- cuo
- 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 - Fee Related
Links
- 239000002887 superconductor Substances 0.000 claims description 38
- 239000013078 crystal Substances 0.000 claims description 7
- 239000010409 thin film Substances 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 3
- 150000001875 compounds Chemical class 0.000 claims 2
- 239000010410 layer Substances 0.000 description 31
- 239000002131 composite material Substances 0.000 description 16
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 229910015901 Bi-Sr-Ca-Cu-O Inorganic materials 0.000 description 4
- 238000000151 deposition Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000002356 single layer Substances 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 229910002480 Cu-O Inorganic materials 0.000 description 1
- 230000005668 Josephson effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
Landscapes
- Physical Vapour Deposition (AREA)
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
- Containers, Films, And Cooling For Superconductive Devices (AREA)
Description
【発明の詳細な説明】 産業上の利用分野 本発明は、超電導弱接合に関する。より、詳細には、
複合酸化物超電導体でジョセフソン効果を実現する超電
導弱接合に関する。TECHNICAL FIELD The present invention relates to a superconducting weak junction. More specifically,
It relates to a superconducting weak junction that realizes the Josephson effect in a complex oxide superconductor.
従来の技術 トンネル型ジョセフソン素子は、一対の超電導体の間
に極薄い非超電導体を挟んで成立する。この非超電導体
の厚さは、ジョセフソン素子を構成する超電導体のコヒ
ーレンス長さにより決定される。このため、複合酸化物
超電導体でトンネル型ジョセフソン素子を作製しようと
すると、前記の非超電導体の厚さは、数十Å程度でなけ
ればならない。2. Description of the Related Art A tunnel type Josephson element is formed by sandwiching an extremely thin non-superconductor between a pair of superconductors. The thickness of the non-superconductor is determined by the coherence length of the superconductor forming the Josephson device. Therefore, if a tunnel-type Josephson device is to be manufactured with a complex oxide superconductor, the thickness of the non-superconductor must be about several tens of liters.
この加工は、非常に困難なため、複合酸化物超電導体
を用いた超電導弱接合は、マイクロブリッジ型と称する
一対の超電導体をいわゆる「くびれ」である微小な超電
導体で結んだ構造のものが報告されているだけである。Since this processing is extremely difficult, a superconducting weak junction using a composite oxide superconductor has a structure in which a pair of superconductors called microbridge type are connected by a minute superconductor that is a so-called "constriction". It has only been reported.
発明が解決しようとする課題 上記のマイクロブリッジ型ジョセフソン素子は、微細
加工を必要とし、工業的には再現性に乏しく、トンネル
型ジョセフソン素子が必然とされている。ところが、非
超電導体を数十Åの厚さに堆積することは、困難である
ばかりでなく、非超電導体と超電導体との間の相互拡散
により、いわゆるシャープな界面を形成することができ
ない。DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The above microbridge type Josephson element requires fine processing and is poor in reproducibility industrially, and a tunnel type Josephson element is inevitable. However, it is not only difficult to deposit a non-superconductor to a thickness of several tens of liters, but also a so-called sharp interface cannot be formed due to mutual diffusion between the non-superconductor and the superconductor.
そこで、本発明の目的は、上記従来技術の問題点を解
決した複合酸化物超電導体によるトンネル型の超電導弱
接合を提供することにある。Therefore, an object of the present invention is to provide a tunnel-type superconducting weak junction using a complex oxide superconductor that solves the above-mentioned problems of the prior art.
課題を解決するための手段 本発明に従うと、複合酸化物超電導体の超電導弱接合
において、十分な厚さに堆積された高い超電導臨界温度
を有する一対の複合酸化物超電導体薄膜間に、前記複合
酸化物超電導体薄膜を構成する複合酸化物の結晶に対し
て構成する層の数が過大または過少で少なくとも１層の
CuO2層を有する結晶の複合酸化物が挟まれていることを
特徴とする超電導弱接合が提供される。Means for Solving the Problems According to the present invention, in a superconducting weak junction of a composite oxide superconductor, between the pair of composite oxide superconductor thin films having a high superconducting critical temperature deposited to a sufficient thickness, the composite If the number of layers constituting the crystal of the composite oxide constituting the oxide superconductor thin film is too large or too small, at least one layer is formed.
A weak superconducting junction is provided, characterized in that a crystalline complex oxide having a CuO 2 layer is sandwiched.
本発明の超電導弱接合に好適な複合酸化物超電導体と
しては、 Bi2Sr2Ca2Cu3O10+X で表される組成を有する複合酸化物を挙げることができ
る。Examples of the composite oxide superconductor suitable for the weak superconducting junction of the present invention include a composite oxide having a composition represented by Bi 2 Sr 2 Ca 2 Cu 3 O 10 + X.
作用 本発明の超電導弱接合は、十分な厚さに堆積された高
い超電導臨界温度を有する一対の複合酸化物超電導体薄
膜間に、前記複合酸化物超電導体薄膜を構成する複合酸
化物の結晶に対して構成する層の数が過大または過少で
ある結晶を有する複合酸化物が挟まれていることを特徴
とする。すなわち、複合酸化物超電導体は、例えば上記
の Bi2Sr2Ca2Cu3O10+X で表される組成を有する複合酸化物の場合、２重Bi層を
挟んでSr原子層が配列し、以下CuO2-CaCuO2-Ca-CuO2の
順でペロブスカイト層が並ぶ。この複合酸化物は、超電
導臨界温度Tcが約105Kの超電導体であるが、このCuO2層
が１層または２層の複合酸化物超電導体も確認されてい
る。複合酸化物超電導体においては、一般にTcは、CuO2
層の数と相関関係があり、上記のBi系複合酸化物超電導
体においては、CuO2層が１層のもののTcは約40Kであ
る。Action The superconducting weak junction of the present invention, between a pair of complex oxide superconductor thin films having a high superconducting critical temperature deposited to a sufficient thickness, to the crystal of the complex oxide constituting the complex oxide superconductor thin film. It is characterized in that a composite oxide having crystals having an excessively large number or an excessively small number of layers is sandwiched therebetween. That is, for example, in the case of a complex oxide having a composition represented by the above Bi 2 Sr 2 Ca 2 Cu 3 O 10 + X , the complex oxide superconductor has Sr atomic layers arranged with a double Bi layer interposed therebetween. , And below, the perovskite layers are arranged in the order of CuO 2 —CaCuO 2 —Ca—CuO 2 . This composite oxide is a superconductor having a superconducting critical temperature Tc of about 105 K, but a composite oxide superconductor having one or two CuO 2 layers has been confirmed. In complex oxide superconductors, Tc is generally CuO 2
There is a correlation with the number of layers, and in the above Bi-based complex oxide superconductor, the Tc of one CuO 2 layer is about 40K.
本発明の超電導弱接合は、上記のBi系で実現する場合
は、CuO2層が３層のBi2Sr2Ca2Cu3O10+Xを約1000Åの厚
さに堆積し、その上にCuO2層が１層であるBi-Sr-Ca-Cu-
O系複合酸化物を１層堆積し、さらにCuO2層が３層の上
記Bi系複合酸化物超電導体をやはり約1000Åの厚さに堆
積することによる。CuO2層が１層のBi-Sr-Ca-Cu-O系複
合酸化物を１層の厚さは約10Åであり、CuO2層が３層の
上記Bi系複合酸化物超電導体のコヒーレンス長さに対し
て十分な値になる。必要に応じ、CuO2層が１層のBi-Sr-
Ca-Cu-O系複合酸化物を２層または３層堆積してもよ
い。上記の超電導弱接合は、液体窒素温度でCuO2層が３
層のBi-Sr-Ca-Cu-O系複合酸化物が超電導体となり、CuO
2層が１層のBi-Sr-Ca-Cu-O系複合酸化物は、非超電導体
であることから実現される。When the superconducting weak junction of the present invention is realized by the above-mentioned Bi system, Bi 2 Sr 2 Ca 2 Cu 3 O 10 + X having three CuO 2 layers is deposited to a thickness of about 1000 Å, and is deposited thereon. Bi-Sr-Ca-Cu- with one CuO 2 layer
By depositing one layer of O-based complex oxide and further depositing the above-mentioned Bi-based complex oxide superconductor having three CuO 2 layers to a thickness of about 1000Å. The CuO 2 layer has one layer of Bi-Sr-Ca-Cu-O-based complex oxide, and the thickness of one layer is about 10Å, and the coherence length of the above Bi-based complex oxide superconductor with three layers of CuO 2 layer. It is a sufficient value for If necessary, a CuO 2 layer is a single layer of Bi-Sr-
Two or three layers of Ca-Cu-O based composite oxide may be deposited. The above superconducting weak junction has a CuO 2 layer of 3 at liquid nitrogen temperature.
Layer Bi-Sr-Ca-Cu-O-based composite oxide becomes a superconductor,
The Bi-Sr-Ca-Cu-O-based composite oxide having two single layers is realized because it is a non-superconductor.
本発明の超電導弱接合は、非超電導体をいわば「層欠
陥」を有するため超電導性を失った複合酸化物超電導体
で構成しているので、複合酸化物超電導体との界面にお
いて、相互拡散等の問題は一切生じないので、界面が非
常にシャープになる。In the superconducting weak junction of the present invention, the non-superconductor is composed of a composite oxide superconductor that has lost superconductivity because it has "layer defects", so to speak, at the interface with the composite oxide superconductor, interdiffusion Since the problem of does not occur at all, the interface becomes very sharp.
本発明の超電導弱接合を形成するには、MBE法または
スパッタリング法等で複合酸化物超電導体結晶の各層を
１層ずつ積み上げる方法によることが好ましい。In order to form the superconducting weak junction of the present invention, it is preferable to deposit each layer of the complex oxide superconductor crystal one by one by the MBE method or the sputtering method.
実施例 Bi-Sr-Ca-Cu-O系複合酸化物を用いて本発明の超電導
弱接合を形成した。形成方法は、スパッタリング法であ
り、MgO単結晶基板の（100）面に形成した。ターゲット
としてBi、Sr、CaおよびCuそれぞれが単独にスパッタリ
ング可能であるようにシャッターにより制御した。最初
にCuO2層が３層のBi2Sr2Ca2Cu3O10+Xを約1000Åの厚さ
に堆積し、次にCuO2層が１層のBi2Sr2CuO6+Xを１層堆積
し、さらにBi2Sr2Ca2Cu3O10+Xを約1000Åの厚さに堆積
して本発明の超電導弱接合を作製した。Example A superconducting weak junction of the present invention was formed using a Bi-Sr-Ca-Cu-O-based composite oxide. The formation method was a sputtering method, and the MgO single crystal substrate was formed on the (100) plane. The target was controlled by a shutter so that Bi, Sr, Ca and Cu can be sputtered independently. First of all, a CuO 2 layer was deposited with 3 layers of Bi 2 Sr 2 Ca 2 Cu 3 O 10 + X to a thickness of about 1000Å, and then a CuO 2 layer was deposited with 1 layer of Bi 2 Sr 2 CuO 6 + X. The superconducting weak junction of the present invention was prepared by depositing layers and further depositing Bi 2 Sr 2 Ca 2 Cu 3 O 10 + X to a thickness of about 1000Å.
液体窒素温度（77.3K）でBi2Sr2Ca2Cu3O10+X層は、完
全に抵抗がなくなり、また、ジョセフソン電流が流れる
ことを確認した。At the liquid nitrogen temperature (77.3K), it was confirmed that the Bi 2 Sr 2 Ca 2 Cu 3 O 10 + X layer was completely free of resistance and the Josephson current flowed.
発明の効果 本発明の超電導弱接合によれば、複合酸化物超電導体
による高性能なトンネル型ジョセフソン素子が簡単に実
現できるものである。EFFECTS OF THE INVENTION According to the superconducting weak junction of the present invention, a high-performance tunnel type Josephson device using a complex oxide superconductor can be easily realized.
Claims (2)
て、十分な厚さに堆積された高い超電導臨界温度を有す
る一対の複合酸化物超電導体薄膜間に、前記複合酸化物
超電導体薄膜を構成する複合酸化物の結晶に対して構成
する層の数が過大または過少で少なくとも１層のCuO2層
を有する結晶の複合酸化物が挟まれていることを特徴と
する超電導弱接合。1. In a superconducting weak junction of a complex oxide superconductor, the complex oxide superconductor thin film is formed between a pair of complex oxide superconductor thin films having a high superconducting critical temperature deposited to a sufficient thickness. 2. A superconducting weak junction characterized in that the compound oxide of the crystal having at least one CuO 2 layer is sandwiched between the crystals of the compound oxide having an excessive or excessive number of layers.
に記載の超電導弱接合。2. The complex oxide superconductor has a composition represented by Bi 2 Sr 2 Ca 2 Cu 3 O 10 + X.
Superconducting weak junction described in.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63249427A JP2501629B2 (en) | 1988-10-03 | 1988-10-03 | Superconducting weak junction |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63249427A JP2501629B2 (en) | 1988-10-03 | 1988-10-03 | Superconducting weak junction |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0297074A JPH0297074A (en) | 1990-04-09 |
| JP2501629B2 true JP2501629B2 (en) | 1996-05-29 |
Family
ID=17192812
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63249427A Expired - Fee Related JP2501629B2 (en) | 1988-10-03 | 1988-10-03 | Superconducting weak junction |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2501629B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9766111B2 (en) | 2012-10-15 | 2017-09-19 | Denso Corporation | Liquid surface detector |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2790494B2 (en) * | 1989-10-13 | 1998-08-27 | 松下電器産業株式会社 | Superconducting element |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63239256A (en) * | 1987-03-27 | 1988-10-05 | Showa Denko Kk | Phenylalanine derivative and proteinase-inhibiting agent |
| JPH02177381A (en) * | 1988-09-22 | 1990-07-10 | Semiconductor Energy Lab Co Ltd | Tunnel junction element of superconductor |
-
1988
- 1988-10-03 JP JP63249427A patent/JP2501629B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9766111B2 (en) | 2012-10-15 | 2017-09-19 | Denso Corporation | Liquid surface detector |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0297074A (en) | 1990-04-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |