SIST EN IEC 61788-22-2:2022

Normal state resistance and critical current measurement - High-Tc Josephson junction (IEC 61788-22-2:2021)

This part of IEC 61788 is applicable to high-Tc Josephson junctions. It specifies terms,
definitions, symbols and the measurement and estimation method for normal state resistance
(Rn) and intrinsic critical current (Ici), based on a combination of selecting a data set from
measured U–I curves with a geometric mean criterion and fitting a hyperbolic function to that
data set.

Supraleitfähigkeit - Teil 22-2: Messung des Normalleitungswiderstands und des kritischen Stroms - HTS Josephson Kontakt (IEC 61788-22-2:2021)

Mesure de la résistance à l’état normal et du courant critique - Jonction Josephson à Tc élevée (IEC 61788-22-2:2021)

L’IEC 61788-22-2:2021 est applicable aux jonctions Josephson à T_c élevée. Elle spécifie les termes, définitions et symboles, ainsi que la méthode de mesure et d’estimation de la résistance à l’état normal (R_n) et du courant critique intrinsèque (I_ci) fondée sur l’association de la sélection d’un ensemble de données à partir des courbes U–I mesurées avec un critère de moyenne géométrique et de l’ajustement d’une fonction hyperbolique à cet ensemble de données.

Merjenje upornosti v normalnem stanju in merjenje kritičnega toka - Spoj "High-Tc Josephson" (IEC 61788-22-2:2021)

Ta del standarda IEC 61788 se uporablja za spoje »High-Tc Josephson«. Določa izraze, definicije, simbole ter metodo za merjenje in ocenjevanje upornosti v normalnem obratovalnem stanju (Rn) in intrinzičnega kritičnega toka (Ici) na podlagi kombinacije izbire niza podatkov iz izmerjenih krivulj U–I s kriterijem geometrijske sredine ter prilagajanja hiperbolične funkcije temu nizu podatkov.

General Information

• Status: Published
• Publication Date: 19-Dec-2021
• ICS: 17.220.20 - Measurement of electrical and magnetic quantities
• ICS: 29.050 - Superconductivity and conducting materials
• Technical Committee: I09 - Imaginarni 09
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 10-Dec-2021
• Due Date: 14-Feb-2022
• Completion Date: 20-Dec-2021
• Ref Project: EN IEC 61788-22-2:2021 - Superconductivity - Part 22-2: Normal state resistance and critical current measurement - High-Tc Josephson junction

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN IEC 61788-22-2:2022
01-februar-2022
Merjenje upornosti v normalnem stanju in merjenje kritičnega toka - Spoj "High-Tc
Josephson" (IEC 61788-22-2:2021)
Normal state resistance and critical current measurement - High-Tc Josephson junction
(IEC 61788-22-2:2021)
Supraleitfähigkeit - Teil 22-2: Messung des Normalleitungswiderstands und des
kritischen Stroms - HTS Josephson Kontakt (IEC 61788-22-2:2021)
Mesure de la résistance à l’état normal et du courant critique - Jonction Josephson à Tc
élevée (IEC 61788-22-2:2021)
Ta slovenski standard je istoveten z: EN IEC 61788-22-2:2021
ICS:
17.220.20 Merjenje električnih in Measurement of electrical
magnetnih veličin and magnetic quantities
29.050 Superprevodnost in prevodni Superconductivity and
materiali conducting materials
SIST EN IEC 61788-22-2:2022 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN IEC 61788-22-2:2022

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SIST EN IEC 61788-22-2:2022


EUROPEAN STANDARD EN IEC 61788-22-2

NORME EUROPÉENNE

EUROPÄISCHE NORM
November 2021
ICS 29.050

English Version
Superconductivity - Part 22-2: Normal state resistance and
critical current measurement - High-T Josephson junction
c
(IEC 61788-22-2:2021)
Supraconductivité - Partie 22-2: Mesure de la résistance à Supraleitfähigkeit - Teil 22-2: Messung des
l'état normal et du courant critique - Jonction Josephson à Normalleitungswiderstands und des kritischen Stroms -
T élevée HTS Josephson Kontakt
c
(IEC 61788-22-2:2021)
(IEC 61788-22-2:2021)
This European Standard was approved by CENELEC on 2021-11-25. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.


European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN IEC 61788-22-2:2021 E

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SIST EN IEC 61788-22-2:2022
EN IEC 61788-22-2:2021 (E)
European foreword
The text of document 90/484/FDIS, future edition 1 of IEC 61788-22-2, prepared by IEC/TC 90
“Superconductivity” was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
EN IEC 61788-22-2:2021.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2022–08–25
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2024–11–25
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 61788-22-2:2021 was approved by CENELEC as a
European Standard without any modification.
2

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SIST EN IEC 61788-22-2:2022
EN IEC 61788-22-2:2021 (E)
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod), the
relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 61788-22-1 - Superconductivity - Part 22–1: EN 61788-22-1 -
Superconducting electronic devices -
Generic specification for sensors and
detectors
IEC 60050-815 2015 International Electrotechnical Vocabulary - - -
Part 815: Superconductivity
IEC 60617 - Graphical symbols for diagrams - -


3

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SIST EN IEC 61788-22-2:2022




IEC 61788-22-2

®


Edition 1.0 2021-10




INTERNATIONAL



STANDARD




NORME


INTERNATIONALE
colour

inside










Superconductivity –

Part 22-2: Normal state resistance and critical current measurement –

High-T Josephson junction:
c



Supraconductivité –

Partie 22-2: Mesurage de la résistance à l’état normal et du courant critique –


Jonction Josephson à T élevée
c













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 29.050 ISBN 978-2-8322-1039-7




Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN IEC 61788-22-2:2022
– 2 – IEC 61788-22-2:2021 © IEC 2021
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Symbols . 8
5 Principle of measurement method . 9
6 Apparatus . 9
6.1 General . 9
6.2 Cryogenic system . 9
6.3 Electrical measurement system . 10
6.4 Circuitry . 10
7 Estimation of normal state resistance (R ) and intrinsic critical current (I ) . 11
n ci
7.1 Calculation method . 11
7.2 Geometric mean criterion for hyperbolic function fitting . 12
8 Standard uncertainty . 12
8.1 General . 12
8.2 Type A uncertainty . 12
8.3 Type B uncertainty . 14
8.3.1 General . 14
8.3.2 Temperature . 14
8.3.3 Voltage measurement . 16
8.3.4 Current measurement . 16
8.4 Budget table . 17
8.5 Uncertainty requirement . 18
9 Test report . 18
9.1 Identification of test device . 18
9.2 R value . 18
n
9.3 I value . 18
ci
9.4 Standard uncertainty . 18
9.5 Atmospheric pressure . 18
9.6 Miscellaneous optional report . 18
Annex A (informative) Calculation technique and practical application to high-T
c
Josephson junctions . 20
A.1 General . 20
A.2 Hyperbolic function fitting method . 20
A.3 Geometric mean method . 21
A.4 Combined method . 22
A.5 Estimation of R , I , u and u . 23
n ci A,R A,I
A.5.1 General . 23
A.5.2 High-T Josephson junction (JL350) . 23
c
A.5.3 High-T Josephson junction (JL351) . 25
c
A.5.4 High-T Josephson junction (TUT) . 27
c
Annex B (informative) Practical application to low-T Josephson junctions . 30
c

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IEC 61788-22-2:2021 © IEC 2021 – 3 –
B.1 General . 30
B.2 Estimation of R , I , u and u . 30
n ci A,R A,I
B.2.1 General . 30
B.2.2 Low-T Josephson junction (IU1) . 30
c
B.2.3 Low-T Josephson junction (IU2) . 31
c
B.2.4 Low-T Josephson junction (IU3) . 32
c
B.2.5 Low-T Josephson junction (IU4) . 34
c
Bibliography . 35

Figure 1 – Typical circuitry for voltage-current (U–I) characteristic curve measurement . 10
Figure 2 – Ideal U–I characteristic curve (red line) and hyperbolic function (RSJ) model
curve (dotted line) . 11
Figure 3 – Geometric mean criterion and RSJ model fitting for TUT-JJ05 at 75,8 K . 15
Figure 4 – Geometric mean criterion and RSJ model fitting for TUT-JJ05 at 76,3 K . 16
Figure A.1 – U–I curve based on resistively shunted junction (RSJ) model . 21
Figure A.2 – U–I curve affected by noise-rounding and self-heating . 21
Figure A.3 – Application of geometric mean method to ideal U–I in Figure A.1 . 22
Figure A.4 – Application of geometric mean method to U–I with noise-rounding and
self-heating effects in Figure A.2. 23
Figure A.5 – U–I curve of JL350 . 24
Figure A.6 – Application of geometric mean method to Figure A.5 . 24
Figure A.7 – Result of RSJ model fitting for JL350 . 25
Figure A.8 – U–I curve of JL351 . 26
Figure A.9 – Application of geometric mean method to Figure A.8 . 26
Figure A.10 – Result of RSJ model fitting for JL351 . 27
Figure A.11 – U–I curve of TUT with a small I . 28
m
Figure A.12 – Application of geometric mean method to TUT . 28
Figure A.13 – Application of adjusted geometrical mean method to TUT . 29
Figure A.14 – Result of RSJ model fitting for TUT . 29
Figure B.1 – Application of geometric mean method to IU1 . 31
Figure B.2 – Result of RSJ model fitting for IU1 . 31
Figure B.3 – Application of geometric mean method to IU2 . 32
Figure B.4 – Result of RSJ model fitting for IU2 . 32
Figure B.5 – Application of geometric mean method to IU3 . 33
Figure B.6 – Result of RSJ model fitting for IU3 . 33
Figure B.7 – Application of geometric mean method to IU4 . 34
Figure B.8 – Result of RSJ model fitting for IU4 . 34

Table 1 – Typical relative standard Type A uncertainty for high-T Josephson junctions . 14
c
Table 2 – Budget table for R . 17
n
Table 3 – Budget table for I . 17
ci
Table A.1 – R , I , u and u values of high-T Josephson junctions . 23
n ci A,R A,I c
Table B.1 – R , I , u and u values of low-T Josephson junctions . 30
n ci A,R A,I c

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

SUPERCONDUCTIVITY –

Part 22-2: Normal state resistance and critical
current measurement – High-T Josephson junction
c

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
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preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 61788-22-2 has been prepared by IEC technical committee 90: Superconductivity. It is an
International Standard.
The text of this International Standard is based on the following documents:
FDIS Report on voting
90/484/FDIS 90/486/RVD

Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.

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SIST EN IEC 61788-22-2:2022
IEC 61788-22-2:2021 © IEC 2021 – 5 –
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
A list of all parts in the IEC 61788 series, published under the general title Superconductivity,
can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.

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INTRODUCTION
IEC 61788-22 (all parts) is a series of International Standards on superconductor electronic
devices. Superconductivity offers various possibilities of realizing sensors and detectors for a
variety of measurands. Several types of superconductor sensors and detectors have been
developed, using such features as superconducting energy gaps, sharp normal-
superconducting transition, nonlinear current-voltage characteristics, superconducting coherent
states and quantization of magnetic flux. Superconductors are influenced by interaction with
electromagnetic fields, photons, ions, etc. The superconductor sensors and detectors have
extremely high performance in resolution, time response and sensitivity, which cannot be
realized by any other sensors and detectors.
IEC 61788-22-1 lists various types of superconductor sensors and detectors. A key element of
some sensors and detectors is Josephson junction. The superconductor material types used for
Josephson junctions are divided into two categories: low-T superconductor (LTS) and high-T
c c
superconductor (HTS). This document (IEC 61788-22-2) defines a measurement method of
normal state resistance (R ) and intrinsic critical current (I ) of HTS Josephson junctions, which
n ci
are used for magnetic measurement with superconductor quantum interference device (SQUID),
detection of millimetre to terahertz band radiation and other applications.
The measurement method covered in this document is intended to give an appropriate and
agreeable technical base for those engineers working in the field of superconductor technology.
Although the mechanism of high-T superconductivity is under investigation, the occurrence of
c
the Josephson effect in such weak link structures as bicrystal, step-edge and ramp edge is
reliable, and characteristic parameters for conventional LTS Josephson junctions are valid also
for HTS Josephson junctions. The important parameters of HTS Josephson junctions for
designing superconductor devices are normal state resistance (R ) and critical current (I ),
n c
which are combined as I R product that is obtained experimentally. At this moment, most HTS
c n
Josephson junctions exhibit a non-hysteretic characteristic voltage-current (U–I) curve, which
is typical for superconductor/normal-conductor/superconductor (SNS) junctions. On U–I curves,
two types of distortions are often observed: noise-rounding and self-heating effects. Especially,
maximum current values without voltage drop on the U–I curves are often considerably reduced
because of the noise-rounding effect, and therefore it is difficult to estimate an intrinsic critical
current value. This document provides a method to obtain intrinsic values by selecting a data
set range to eliminate the distortions and by fitting a model function even when two effects are
present.
The critical current obtained by this standard method is therefore called intrinsic critical current
with the variable symbol of I , eliminating the noise-rounding effect on U–I curves. On the other
ci
hand, the normal state resistance is insensitive to the noise rounding and it is possible to avoid
the self-heating effect, so that the variable symbol R is used. The I R product is more
n ci n
essential for designing superconductor devices than the I R product. I values estimated by
c n ci
this document are usually higher than experimental I values.
c
Practical application of this document to HTS Josephson junctions is shown in Annex A. The
estimation method in this document is applied to SNS-type LTS Josephson junctions to check
universality in Annex B.

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SIST EN IEC 61788-22-2:2022
IEC 61788-22-2:2021 © IEC 2021 – 7 –
SUPERCONDUCTIVITY –

Part 22-2: Normal state resistance and critical
current measurement – High-T Josephson junction
c



1 Scope
This part of IEC 61788 is applicable to high-T Josephson junctions. It specifies terms,
c
definitions, symbols and the measurement and estimation method for normal state resistance
(R ) and intrinsic critical current (I ), based on a combination of selecting a data set from
n ci
measured U–I curves with a geometric mean criterion and fitting a hyperbolic function to that
data set.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 61788-22-1, Superconductivity – Part 22-1: Superconducting electronic devices – Generic
specification for sensors and detectors
IEC 60617, Graphical symbols for diagrams: available at http://std.iec.ch/iec60617
IEC 60050-815:2015, International Electrotechnical Vocabulary – Part 815: Superconductivity:
(available at http://www.electropedia.org/
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
U–I characteristic curve
V–I characteristic curve
I–V characteristic curve
data set of voltage drop between two superconductors of a Josephson junction and current
applied to the junction

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3.2
normal state resistance
R
n
normal resistance
resistance between two superconductors forming a Josephson junction in a normal-conducting
state
Note 1 to entry: In a Josephson bridge junction, a normal state resistance is also defined as the resistance at a
bias current that suppresses superconductivity well above critical current, when the self-heating effect is negligible.
Note 2 to entry: In a Josephson tunnel junction, a normal state resistance is also defined as the tunnelling resistance
at a bias voltage well above 2Δ/e, where Δ is the energy gap and e is the elementary electric charge, when the self-
heating effect is negligible.
3.3
intrinsic critical current
I
ci
maximum direct current that can be applied to a Josephson junction without causing a voltage
drop across the junction in the absence of noise-rounding on a U–I characteristic curve
Note 1 to entry: Critical current (I ) is the maximum direct current value that can be applied to a Josephson junction
c
experimentally so that it can be regarded as flowing without resistance (IEC 61788-22-1).
Note 2 to entry: The method described in this document estimates I , the value of which is usually higher than I .
ci c
3.4
geometric mean
square root of the product of dU/dI and U/I obtained from a U–I characteristic curve
3.5
noise-rounding effect
effect of noise on a U–I characteristic curve
Note 1 to entry: The U–I curve shape near I is rounded from an ideal shape by the noise-rounding effect. Because
ci
of this, an I value is lower than the I value.
c ci
3.6
self-heating effect
effect of power dissipation due to transport current applied to a Josephson junction on a U–I
characteristic curve
Note 1 to entry: The current generates heat, and a U–I curve shape in a high current region well above I deviates
ci
upward above a straight line corresponding to R .
n
4 Symbols
U voltage drop across two superconductors conn
...