[ PCO Home Page ] [ Table of Contents of NEWSLETTER # 68 ]

........ published in NEWSLETTER # 68

By Professors J. Bok, ESPCI, Paris (France)

This volume (NATO ASI SERIES B371) contains the lectures given at the NATO ASI held at the Institut d'Etudes Scientifiques de Cargese, Corsica (France) in September 1997.

What set this book apart from similar volumes in this field is the fact that the authors are very distinguished international experts yet, thanks to the insistance of the co-editors, they have written very pedagogical papers. Therefore the book is of great interest to all scientists and engineers working in this field and also to all students studying this topic. The book contains up-to-date information on the progress in the field and covers the theory, an overview of selected experiments on carefully characterized samples and also some of the most relevant applications. The readership will include physicists, chemists, electrical and electronic engineers as well as decision-makers and students in all these fields. Although a first science degree is a prerequisite to read such a volume, the editors (Julien Bok, Guy Deutscher, Davor Pavuna, Stuart A. Wolf) have taken great care that the introductory chapters cover all elementary notions of interest to beginners.

It is evident from all contributions that great progress has been made in preparation and in-depth characterisation of samples of various cuprate families, including detailed studies of electron doped oxides. The reproducible, high resolution experimental results by all leading groups provide a remarkable body of knowledge that still remains elusive to the coherent all-inclusive microscopic theory of high-Tc superconductivity.

There is now well established evidence for the existence of two transition lines in the electronic phase diagram of HTSC cuprates (in temperature vs doping diagram), even though the nature of the so-called pseudogap and the exact nature of the insulator to metal (superconductor) transition remain disputed. In the superconducting state a majority of experiments indicate a dominant d-wave symmetry in the underdoped to optimally doped samples. There are, however, some notable exceptions: there is no evidence for d-wave component in electron doped cuprates, Sharvin experiments on LSCO give a finite minimum gap and one electronic Raman experiment on Hg 2201 compound is not compatible with d-wave but rather with extended s-wave (with nodes). Only a few experiments have been carried out systematically in the overdoped regime. One photoemission experiment in strongly overdoped BSCCO indicates a finite minimum gap. These results have yet to be confirmed by other groups.

The first commercial applications of HTSC materials are readily available and they include the energy storage appliances, first magnets as well as radar and passive telecommunication components. Moreover, some of these applications already provide jobs for young researchers in Europe, the USA, China and Israel. Despite the overall progress of the many body theory and itinerant electron models, the greatest challenge remains the development of the full microscopic theory for high-Tc superconducting oxides.
Reference books: B371, E263, E343

[ PCO Home Page ]