Mechanisms of High Temperature Superconductivity

Since the discovery by Bednorz and Müller of Cu-O alloys displaying high temperature superconductivity, great energy has been put into research in this field. One of the most important and interesting issues, and the subject of this volume, is the clarification of the microscopic origin and mechanism of high temperature superconductivity. This book discusses the latest experimental results on magnetic, optical, electrical, thermal and mechanical properties of the Cu-O and Bi-O superconductors, as well as proposed theoretical models of the mechanisms. The participants in the symposium agreed that for the high Tc Cu-O superconductors electron correlation effects are of central importance. For the Bi-O superconductors the main topic was whether the mechanism of superconductivity is the same as that of high Tc Cu-O superconductors. What was and what was not resolved at the symposium is summarized at the end of the volume.

Contenu

I Plenary Lecture.- The Development of the High-Temperature Superconductivity Field.- II Theoretical Approach.- Spin-Polaron Pairing Mechanism in the High Tc Copper Oxides.- The Importance of Correlation, Multiplet Structure, Hybridization and Symmetry in the Electronic Structure of High Tc Cu Compounds.- Finite Systems Studies and the Mechanism of High Tc.- What Can We Learn from Small-Cluster Studies on CuO2 and Related Models?.- Recent Numerical Studies on Models for High-Tc Superconductors.- Fermi Liquid and Non Fermi Liquid Phases of the Extended Hubbard Model.- Motion of Holes in Magnetic Insulators.- Fractional Quantization in High-Temperature Superconductivity.- Recent Studies of the Cu d-d Excitation Model.- Electronic Structure, Fermi Liquid and Excitonic Superconductivity in the High Tc Cu-Oxides.- Local-Spin-Density-Functional Approach to High-Tc Copper Oxides.- III Experimental Approach.- III.1 Magnetic.- Quasielastic and Inelastic Spin Fluctuations in Superconducting La2-xSrxCuO4.- Two Dimensional Quantum Spin Fluid - Progenitor of High Temperature Superconductivity.- Nuclear Resonance Studies of YBa2Cu3O7-?.- NMR in High Tc Oxide Superconductors.- Charge Differentiation of Inequivalent Cu Sites of YBa2Cu3Oy (6.0?y?6.91) Investigated by NQR and NMR.- Mössbauer Studies of High-Tc Oxides.- III.2 Optical.- Photoemission Studies of High-Tc Cu Oxides: Character of Doped Oxygen Holes and Pairing Mechanisms.- Experimental Approach to the Mechanism of High-Tc Superconductivity.- Extensive Study of the Optical Spectra for High Tc Cuprates and Related Oxides.- Raman Scattering Spectroscopy in High Temperature Superconductors.- III.3 Tunneling.- Tunneling and the Energy Gap in the High-Temperature Superconductors.- Energy Gap Measurement Made on Cryogenically Cleaved Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O Surfaces.- III.4 Transport.- Transport and Magnetic Properties of (La1-xSr)2CuO4.- Anisotropic Transport in Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O.- Transport Studies on High Tc Oxides.- III.5 Thermal.- Recent Experimental Studies on High-Tc Oxides at IMS.- III.6 Structural.- Substitution Effects in High-Tc Superconductive Oxides.- Strong Dependence of Tc on Hole Concentration in CuO2 Sheets.- Electron Microscopic Study on Ti-Ba-Cu-O Superconductor Oxides.- Orthorhombic-II Superstructure and Significance of Oxygen Ordering for Superconductivity in YBa2Cu3O7-?.- IV Superconductivity of Ba-K-Bi-O Compounds.- A Comparison Between Bi-O and Cu-O Based Superconductors.- V Summary of Discussion Session.- Notes on Hakone Conference.- Index of Contributors.- Group Photograph and List of Participants.