High-temperature superconductivity physics

Author: Han Rushan
Editor-in-Chief: Qu Ding
Publisher:
Publish Date: 1999-11-01
Features:
Excerpt: The introduction from the discovery in 1986 of a high-temperature copper oxide superconductor sparked a research boom that has lasted over a decade. In this global wave of enthusiasm, the breadth of research fields and the depth of the issues addressed are rare in the last few decades. Vast research results are scattered across tens of thousands of papers in hundreds of conferences and journals. Over a thousand monographs, including various specialized reviews, have been published. However, few textbooks suitable for students are available, especially in China. Those that exist mostly cover only early research findings. Over the past decade, the author has given numerous presentations on "New Developments in High-Temperature Superconductivity" in various settings, deeply feeling the need for a specialized textbook. Writing such a book is challenging, primarily because research is still progressing rapidly, and no unified theoretical explanation exists. The author hopes to use core physical problems as the main thread, revealing the challenges high-temperature superconductors pose to traditional condensed matter physics through different aspects of various physical properties. This will allow readers to gradually grasp how traditional physical concepts and theories fail through experiments. The author aims to avoid getting bogged down in the details of experimental techniques, focusing instead on the physical essence embedded in experiments. The author also hopes to minimize the use of mathematics, highlighting the physical picture. This will enable readers to quickly enter the forefront of high-temperature superconductivity research and more rapidly reach the core aspects of the issues. The difficulty of writing such a book is evident. High-temperature superconductors exhibit many astonishing properties. Over the decade since the discovery of high-temperature superconductivity, while researchers continue to search for new materials with higher Tc values, they have also devoted significant effort to confirming, enriching, and understanding these peculiar phenomena. This task is extremely important because strong electron correlation effects and strong magnetic coupling effects seem to be the key. People must find a way to modify the BCS theory or even the Landau Fermi liquid theory to explain these numerous anomalous properties. For decades, the Landau Fermi liquid theory and the BCS (Bardeen-Cooper-Schrieffer) theory have been proven correct in a wide range of materials. However, they face severe challenges in the face of high-temperature superconductors. This situation forces us to develop these theories to more comprehensively incorporate strong electron interactions. It is certain that the anomalous properties in the normal and superconducting states of high-temperature superconductors will lead to a major transformation in our understanding of solids. High-temperature superconducting materials are among the most complex materials ever studied. They require high-quality large single crystals with extremely high purity and uniformity to study their many anisotropic intrinsic properties. We will disregard the chronological order of research, focusing instead on the main new phenomena and the important fundamental issues they reflect, as well as the new concepts and ideas that have emerged alongside them. The selected phenomena and fundamental issues have been endorsed and agreed upon by most research groups. Perhaps, or rather, we expect them to withstand the test of time. Due to space constraints, we cannot describe these phenomena and issues in detail, but we will emphasize the physical implications of the results, highlighting their anomalous and peculiar deviations from Fermi liquid theory and BCS theory.