Session B1: 20th Anniversary of High Tc Superconductivity 'Woodstock' Session

The Discovery of High-Tc Superconductivity and the Countdown to the Rally

The guiding ideas on our road towards high-Tc superconductivity and the early work at the IBM Zurich Research Laboratory are briefly addressed. I will shed some light onto the environment and the decisive circumstances that in January 1986 led to the breakthrough with the discovery of superconductivity in the cuprates. The pre-``Woodstock'' period, which lasted less than a year, covers the time in which the Zurich team tested different La$_2$CuO$_4$-based compounds, confirmed the Meissner effect, and studied flux trapping in these new materials. It was also the time in which the news of the discovery started to spread and in which we experienced mixed reactions ranging from silent skepticism to polite (cautious) congratulations. This changed dramatically into excitement with the confirmation of the Zurich results by the Tokyo (S. Tanaka) and the Houston ( C.W. Chu) group, and cumulated in the take-off of the new field at the famous ``Woodstock Meeting of Physics'' after the discovery of the 90 K superconductor.   

High $T_{c}$: The Discovery of RBCO

It was said by Emerson that ``there is no history; there is only biography.'' This is especially true when the events are recounted by a person who, himself, has been heavily involved and the line between history and autobiography can become blurred. However, it is reasonable to say that discovery itself is not a series of accidents but an inevitable product of each development stage of scientific knowledge as was also pointed out by Holden et al. (1) The discovery of RBCO (2,3) with R = Y, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu is no exception. In this presentation, I will briefly recount several events that were crucial to the discovery of RBCO: those before 1986 (4) that sowed the seeds in our group important to our later high temperature superconductivity effort; those in 1986 (5) that were critical to our discovery of the 93 K RBCO soon after the discovery of the 35 K high temperature superconductor by M\"{u}ller and Bednorz (6); and those in 1987 when the barrier of the liquid nitrogen boiling temperature of 77 K was finally conquered. \newline \newline 1. G. J. Holton et al., American Scientist 84, 364 (1996). \newline 2. M. K. Wu et al., Phys. Rev. Lett. 58, 908 (1987). \newline 3. P. H. Hor et al., Phys. Rev. Lett. 58, 1891 (1987). \newline 4. C. W. Chu et al., S. S. Comm. 18, 977 (1976); C. W. Chu and V. Diatchenko, Phys. Rev. Lett. 41, 572 (1978); T. H. Lin et al., Phys. Rev. B(RC) 29, 1493 (1984); J. H. Lin et al., J. Low Temp. Phys. 58, 363 (1985). \newline 5. C. W. Chu et al., Phys. Rev. Lett. 58, 405 (1987); C. W. Chu et al., Science 235, 567 (1987). \newline 6. J. G. Bednorz and K. A. M\"{u}ller, Z. Phys. B64, 189 (1986).   

Some Prehistory to Woodstock

I want to briefly describe the background surrounding two talks that provided a preview of the excitement that was to spill over at the '87 March APS meeting. The first was an unscheduled talk on LaBaCuO by Professor K. Kitazawa on Dec 5, 1986 at an MRS symposium on Superconducting Materials held in Boston. The second was a quasi- public disclosure by Professor Paul Chu regarding his work on superconductivity above liquid nitrogen temperatures on Feb 28, 1987 at UCSB. These talks form part of the prehistory to the what became known as the Wookstock of physics.   

Early High Tc Activity in Japan: The Franco Rasetti Lecture

From 1960 to 1980, R\&D of superconductivity in Japan was carried out mainly to improve A15 superconducting wires and magnets. Improvement of wires were made mainly in the National Institute for Metals, and improvements of superconducting magnets were made in the Japan Atomic Energy Research Institute for future nuclear fusion reactors, the National Railway Laboratory for future maglev trains and also in the Electo-Technical Laboratory for MHD generators. I began the research of BPBO in 1975 and at that time the research of oxide superconductors was limited only to my laboratory in the University of Tokyo. During the study of this new superconductor, we learned quite a lot on how to make ceramic samples, how to measure electrical conductivity and magnetic susceptibility at low temperatures. In 1982, Prof. S. Nakajima organized a rather small group for investigating ``New Superconducting Phenomena,'' and I became a member of the group. In 1985, Nakajima expanded the research group to include more than 5 experimentalists and 5 theoreticians. The title of the research was ``New Superconducting Materials'' and the funds came from the Ministry of Education of Japan. In late October, 1986, we followed the first paper of Bednorz and Muller, and immediately found the material includes high temperature superconductor and reported it to the group meeting held in early November. In early December, we confirmed La$_{2-x}$Ba$_x$CuO$_4$ is the real high temperature superconductor, the critical temperature is 28K. I sent a copy of our paper to Prof. Beasley of California and asked to inform this fact to his colleagues. Asahi Shimbun, the biggest newspaper in Japan announced this in its science section, and then many people knew the high temperature superconductor had been discovered. Then many physicists and chemists rushed to this field very quickly and many kinds of materials were synthesized. In the Government, the Ministry of Education, the Ministry of International Trade and Industry (MITI), and the Agency for Science and Technology began to make new development plans of their own. Superconductivity fever then started in Japan. ISTEC was established in early 1988 under the support of MITI and industries.   

High Tc Superconductivity --1987

The discovery of superconductivity in the cuprate class of conducting oxides brought a flash of sunlight on one of the fields condensed matter physics that many of us had thought was rather mature and fairly well understood. Alas, it was not so. In addition to opening a whole new class of materials to the study of correlated motion of charge carriers, it opened a new mind-set that materials with complex chemical bonding can lead to totally new phenomena. The tasks of materials preparation escalated, and with it came the development of totally new spectral probes of the electron gas and the electronic structure in metals. The task is to use complexity so that the interplay of adjacent correlated motion can be used to generate new phenomena that will in turn perform novel functions.