Theory of High Temperature Superconductivity

Shigeji Fujita, Salvador Godoy (eds.)1402001495, 9781402001499, 9780306482168

Flux quantization experiments indicate that the carriers, Cooper pairs (pairons), in the supercurrent have charge magnitude 2e, and that they move independently. Josephson interference in a Superconducting Quantum Int- ference Device (SQUID) shows that the centers of masses (CM) of pairons move as bosons with a linear dispersion relation. Based on this evidence we develop a theory of superconductivity in conventional and mate- als from a unified point of view. Following Bardeen, Cooper and Schrieffer (BCS) we regard the phonon exchange attraction as the cause of superc- ductivity. For cuprate superconductors, however, we take account of both optical- and acoustic-phonon exchange. BCS started with a Hamiltonian containing “electron” and “hole” kinetic energies and a pairing interaction with the phonon variables eliminated. These “electrons” and “holes” were introduced formally in terms of a free-electron model, which we consider unsatisfactory. We define “electrons” and “holes” in terms of the cur- tures of the Fermi surface. “Electrons” (1) and “holes” (2) are different and so they are assigned with different effective masses: Blatt, Schafroth and Butler proposed to explain superconductivity in terms of a Bose-Einstein Condensation (BEC) of electron pairs, each having mass M and a size. The system of free massive bosons, having a quadratic dispersion relation: and moving in three dimensions (3D) undergoes a BEC transition at where is the pair density.

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Table of contents :
Introduction….Pages 1-18
Superconducting Transition….Pages 19-25
Bloch Electrons….Pages 27-44
Phonon-Exchange Attraction….Pages 45-58
Quantum Statistical Theory….Pages 59-63
Cooper Pairs (Pairons)….Pages 65-76
Superconductors at 0 K….Pages 77-93
Quantum Statistics of Composites….Pages 95-106
Bose-Einstein Condensation….Pages 107-121
The Energy Gap Equations….Pages 123-132
Pairon Energy Gaps. Heat Capacity….Pages 133-146
Quantum Tunneling….Pages 147-161
Flux Quantization….Pages 163-180
Ginzburg-Landau Theory….Pages 181-191
Josephson Effects….Pages 193-206
Compound Superconductors….Pages 207-216
Lattice Structures of Cuprates….Pages 217-225
High-T c Superconductors Below T c ….Pages 227-239
Doping Dependence of T c ….Pages 241-248
Transport Properties Above T c ….Pages 249-258
Out-of-Plane Transport….Pages 259-267
Seebeck Coefficient (Thermopower)….Pages 269-283
Magnetic Susceptibility….Pages 285-294
Infrared Hall Effect….Pages 295-305
d-Wave Cooper Pairs….Pages 307-310
Connection with Other Theories….Pages 311-323
Summary and Remarks….Pages 325-332