Theory of Copper Oxide Superconductors

The objective of this book is to provide an up-to-date comprehensive descr- tion of the Kamimura Suwa model, which is the ?rst of the present rep- sentative two-component theories in high temperature superconductivity. In 1986 George Bednorz and Karl Alex Muller made the remarkable discovery ofsuperconductivitywithanunbelievinglyhighvalueofT = 35K,bysubs- c 2+ 3+ tuting Ba ions for La ions in the antiferromagnetic insulator La CuO . 2 4 Soon after this discoveryT rose to 90K by synthesizing YBa Cu O with c 2 3 7?? ade?citinoxygen. Furtherexplorationfornewcopperoxidesuperconducting materials with higherT led to the discovery of Bi Sr Ca Cu O, Tl Ba Ca c Cu O and Hg Ba Ca Cu O compounds in subsequent years. The new class of copper oxide compounds mentioned above is called cuprates . At present T = 135K under ambient pressure andT = 164K under 31 GPa observed c c in HgBa Ca Cu O are the highest value so far obtained. The Kamimura 2 2 3 8 Suwa model, which was originally developed in 1993, is a theory of these real copper oxide superconducting materials. Since undoped La CuO is a 2 4 Mott Hubbard antiferromagnetic insulator, its electronic structure can not beexplained bytheordinaryone-electron energybandtheory. Inthiscontext the important role of electron-correlation was pointed out. 2+ On theother hand, ad-hole state in each Cu ion in theligand ?eld with octahedral symmetry is orbitally doubly-degenerate so that it is subject to strong Jahn Teller interaction in La CuO. Asaresult,aCuO octahedron 2 4 6 in La CuO is elongated along thec-axis due to the Jahn Teller distortion.

Elucidates an important model for understanding high-Tc superconductivity in copper oxides

Texte du rabat

This is an advanced textbook for graduate students and researchers wishing to learn about high temperature superconductivity in copper oxides, in particular the Kamimura-Suwa (K-S) model. Because a number of models have been proposed since the discovery of high temperature superconductivity by Bednorz and Müller in 1986, the book first explains briefly the historical development that led to the K-S model. It then focuses on the physical background necessary to understand the K-S model and on the basic principles behind various physical phenomena such as electronic structures, electrical, thermal and optical properties, and the mechanism of high temperature superconductivity.

Contenu
Experimental Results of High Temperature Superconducting Cuprates.- Brief Review of Models of High-Temperature Superconducting Cuprates.- Cluster Models for Hole-Doped CuO6 Octahedron and CuO5 Pyramid.- MCSCF-CI Method: Its Application to a CuO6 Octahedron Embedded in LSCO.- Calculated Results of a Hole-Doped CuO5 Pyramid in YBa2Cu3O7??.- Electronic Structure of a CuO5 Pyramid in Bi2Sr2CaCu2O8+?.- The KamimuraSuwa (K-S) Model: Electronic Structure of Underdoped Cuprates.- Exact Diagonalization Method to Solve the KS Hamiltonian.- Mean-Field Approximation for the KS Hamiltonian.- Calculated Results of Many-Electrons Band Structures and Fermi Surfaces.- Normal State Properties of La2?xSrxCuO4.- ElectronPhonon Interaction and ElectronPhonon Spectral Functions.- Mechanism of High Temperature Superconductivity.