Preface
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| Дата: | 2006 |
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Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України
2006
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| Назва видання: | Физика низких температур |
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| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Preface // Физика низких температур. — 2006. — Т. 32, № 4-5. — С. 378-380. — Бібліогр.: 3 назв. — англ. |
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irk-123456789-1208762017-06-14T03:02:28Z Preface High-Tc superconductivity: XX years after the discovery 2006 Article Preface // Физика низких температур. — 2006. — Т. 32, № 4-5. — С. 378-380. — Бібліогр.: 3 назв. — англ. 0132-6414 http://dspace.nbuv.gov.ua/handle/123456789/120876 en Физика низких температур Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України |
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High-Tc superconductivity: XX years after the discovery High-Tc superconductivity: XX years after the discovery |
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High-Tc superconductivity: XX years after the discovery High-Tc superconductivity: XX years after the discovery Preface Физика низких температур |
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Article |
| title |
Preface |
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Preface |
| title_full |
Preface |
| title_fullStr |
Preface |
| title_full_unstemmed |
Preface |
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preface |
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Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України |
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2006 |
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High-Tc superconductivity: XX years after the discovery |
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http://dspace.nbuv.gov.ua/handle/123456789/120876 |
| citation_txt |
Preface // Физика низких температур. — 2006. — Т. 32, № 4-5. — С. 378-380. — Бібліогр.: 3 назв. — англ. |
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Физика низких температур |
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1837105640122613760 |
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Preface
The scientific event that impressed and excited the
whole world, without exaggeration, took place pre-
cisely 20 years ago, in April 1986. It was when the
journal «Zeitschrift fur Physik B: Condensed Matter»
received the five-page article by the Swiss researchers
Georg Bednorz and Alex M�ller from the IBM re-
search laboratory in Z�rich, that went under a very
cautious title (as repeatedly noted), namely «Possible
High-Tc Superconductivity in Ba–La–Cu–O System»,
and was published in the September issue [1]. The ar-
ticle reported results of the observation of a rather
broad superconducting transition occurring in the ce-
ramic compound La2CuO4 doped for becoming metal-
lic with alkali-earth metals Ba, Sr or Ca. The critical
temperature Tc � 30–35 K of the transition was al-
most one and a half as high as the previous record of
Tc � 24 K achieved with great effort in 1973. This pub-
lication, as short as it was, launched a new boom of in-
vestigations of such an outstanding phenomenon as su-
perconductivity, which, by the way, «marked» its
75th anniversary in the same year 1986. Thus, it can
be said with good reason and full certainty that
high-temperature (or high-Tc) superconductivity as
a phenomenon of nature, to which this special issue
of Low Temperature Physics is dedicated, will be
twenty years old this April. It should be noted that
the question of the «age» of high-Tc superconductivity
of copper or «Z�rich oxides», as they are sometimes
called, is not just a matter of an idle curiosity since
«high-temperature superconductivity» in its true sense,
i.e., with Tc > 77 K, was discovered almost a year
later [2].
These results gave an onset to an unprecedented
world-wide boom, whereby a physical phenomenon at-
tracted tremendous attention, not only of physicists
and specialists involved in related areas, but also of
the general public*. Indeed, the article by Bednorz
and M�ller was a real breakthrough, pioneering a fun-
damentally new area of scientific exploration, which
made the many years old dream of high values of Tc
come true. In fact, all subsequent high-Tc compounds,
i.e., the 90-degree yttrium, 110-degree bismuth, 125-de-
gree thallium and, finally, today’s record-breaking
164-degree (under pressure) mercury compounds are
just the results of explorations by physicists and
chemists working in materials science — an unknown
area for the majority of experimenters and theoreti-
cians, which was quite unexpectedly discovered by the
Swiss physicists. Whatever the detailed properties of a
material exhibiting the high-Tc superconductivity are
and whatever type of conductivity or structure it has,
all of the compounds known so far feature one com-
mon element, i.e., planes of CuO2, where the main ac-
tion of the play called «high-Tc superconductivity»
originates and takes place. That is why only G.
Bednorz and A. M�ller can be considered to be the au-
thors, and that is why the priority, justifiably con-
firmed by the Nobel Prize, belongs to them.
As to the memories of the first, remarkable and ro-
mantic, period of investigations into high-Tc super-
conductivity that rapidly involved almost all centers
of physical, chemical and applied research at universi-
ties, institutes, companies and enterprises, it is worth-
while to note numerous newspaper or TV reports of in-
creasingly high Tc’s, as well as positive forecasts and
strong, although exaggerated, hopes for prompt and
universal world-wide energy well-being.
Alas, this has not happened as yet!
There are many reasons for this, but the main one
probably consists in the fact that the new materials
turned out to be dramatically different from conven-
tional superconductors, and they posed problems
which nobody could foresee or anticipate. And al-
though, as expressed by V.L. Ginzburg [3], copper
oxides «should not be separated by a Chinese wall
from other superconducting materials», they consti-
tute a special and, despite an incredible number of
publications (already about 100,000), yet not totally
understood class of conductors. In particular, the fact
that the conductivity of cuprates is formed by starting
from insulating antiferromagnetic systems (which is
due to strong on-site electron-electron correlations) is
an issue that is hard to understand and, moreover,
hard to describe.
Nevertheless, during the twenty years of super-
intensive investigations, high-Tc superconductivity
changed into an independent and vast area of research,
where much has already been done, but still more has
to be done in the future. In particular, missing is a so-
lution of the question about the crucial interaction un-
derlying pairing, which, in turn, is anisotropic. Also
unsolved are many seemingly particular issues, which,
at the same time, are very important for further deve-
lopment of physics of superconductivity and its appli-
* It is interesting to note that in 1987 President Ronald Reagan made a speech at the Plenary Meeting of the American
Physical Society, and at that same time the National Program «High-Temperature Superconductivity» headed by Prime
Minister N.I. Ryzhkov was launched in the USSR with generous funding. Similar measures for the investigation of new
materials and for a hopefully rapid and free application of the results were taken in all industrialized countries.
© V. Loktev, Hans Beck, and V.N. Samovarov, 2006
cation. This fact can be explained (but not justified):
as it turned out soon, the discovery and subsequent ex-
perimental investigation of specially synthesized and
increasingly more perfect high-Tc compounds demon-
strated an insufficient development of important as-
pects of condensed matter theory, which proved to be
«unfit» for an adequate description of properties of
strongly correlated doped metals. Moreover, if we add
to it that the latter exhibit, simultaneously, the fea-
tures of magnetic, disordered and low-dimensional
systems, which before the discovery of high-Tc super-
conductivity were usually studied separately, then the
problems accompanying investigations of these fasci-
nating materials should be clear even to nonspecia-
lists.
Being guest editors, we wished the special issue of
Low Temperature Physics dedicated to the jubilee of
high-Tc superconductivity to contain experimental
and theoretical articles summarizing results in this
area of research, or in related ones. This was indeed
the case for a number of articles, and the reader will
really have the opportunity to get acquainted with
history and state-of-the-art in a number of issues. On
the other hand, many authors understood the task in a
wider sense and decided to report on the latest results
relating not only to copper oxides, but also to other
systems, the investigation of which was caused by and
derived from the high-Tc superconductivity. Equally
favorable treatment was also given to such articles,
following the rule that «everything not prohibited
should be allowed».
The spectrum of the covered problems is quite large:
various experimental techniques used to study the elec-
tronic states and the response to electromagnetic fields
are presented. Special and unexpected properties, such
as the electronic pseudogap in the normal state, the
«stripe phase» and the competition of superconduc-
tivity with orbital current structures are discussed
and «justified» by model calculations. The question
whether «good old» electron-phonon interaction, pos-
sibly combined with the effect of Coulomb repulsion
and acting through a nonadiabatic mechanism, or other
collective modes like spin fluctuations are responsible
for the electronic pairing is analyzed in detail. Theo-
reticians develop quite heavy machinery, such as Gutz-
willer projection for the ground state or the dynamic
mean-field approach for the Hubbard model, in order to
get hold of the secrets of strongly correlated electrons.
Applying these ideas to superconductivity in organic
compounds and in systems of ultra-cold atoms brings
the reader back to interesting domains of low-tempera-
ture superconductivity.
We thought that joining under the same cover arti-
cles on superconductivity of such different orientation
would not merely be a «tribute to fashion or eclecti-
cism», but a direct reflection of the present-day rea-
lity, where specialists of different scientific orien-
tation could find nontrivial relationships between
branches of a wide area of knowledge, which the phys-
ics of superconductivity became after the discovery of
Bednorz and M�ller. The time of groundless advertise-
ment promises, such as forthcoming levitated trains,
very fast and cheap computer techniques, resistless en-
ergy and current transportation in wires over long dis-
tances, large-scale applications for powerful magnets,
motors, generators — and many others — has gone
long ago. But there comes the time of serious, in-depth
research in one of the major, promising and actively
developing exciting areas of solid state physics.
On the other hand, specialists, as well as anybody
interested in the latest achievements and topical (by no
means all) problems of physics of superconductivity,
can see how long the way is that high-Tc superconduc-
tivity has gone through and how great the progress is in
this area. Finally, and one should not wonder about
that, many challenges have not yet been overcome, de-
spite much success. Probably the ways for solving some
of them can be found to some extent in the articles im-
mediately following our introductory words.
Twenty years have passed by very quickly, and now
we are entering the next, third decade. The order of
the day is to achieve maximum Tc under conditions
which are not too different from the normal ones. Of
course, room temperature under ambient pressure
would be an ideal variant in terms of possible applica-
tions. The answers to this, as well as to many other
important questions, including practical ones, will
hopefully be given in the foreseeable future.
In the conclusion, in the name of the Editorial
Board of Low Temperature Physics and on our per-
sonal behalf, we are expressing our sincere gratitude
to all our colleagues for their kind consideration in
preparing their contribution to this jubilee issue. Also,
we are sincerely asking for the understanding of those
authors whose articles for technical reasons or because
of late submission could not be included in the present
issue of the journal, although it is of a double volume.
They will be published in the next issue.
Prof. V. Loktev (Bogolyubov Institute for Theoretical
Physics, Kiev, Ukraine),
Prof. H. Beck (University of Neuchatel, Neuchatel,
Switzerland),
Prof. V. Samovarov (B. Verkin Institute for Low
Temperature Physics and Engineer-
ing, Kharkov, Ukraine).
1. J.G. Bednorz and K.A. M�ller, Z. Phys. B64, 189
(1986).
2. M.K. Wu, J.R. Ashburn, C.J. Torng, P.H. Hor, R.L.
Meng, L. Gao, Z.J. Huang, Y.Q. Wang, and C.W.
Chu, Phys. Rev. Lett. 58, 908 (1987).
3. V.L. Ginzburg, Physics-Uspekhi 43, 573 (2000).
380 Fizika Nizkikh Temperatur, 2006, v. 32, Nos. 4/5
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