Quantum Many-Body Approach to High-Temperature Superconductors: Superexchange, Doping, and Pairing Mechanisms
1. Introduction Since the discovery of high-temperature superconductors (cuprate superconductors) by Bednorz and Müller in 1986, they have become one of the most important research topics in physics and materials science. Unlike conventional low-temperature superconductors, cuprate superconductors exhibit relatively high critical temperatures (Tc), with some materials reported to maintain superconductivity up to 164K under specific conditions. These properties enhance their potential applications in energy storage, power transmission, and quantum computing, driving continuous research efforts to develop high-temperature superconductors into practical technologies. However, the superconducting mechanism of cuprate superconductors remains incompletely understood. The conventional BCS (Bardeen-Cooper-Schrieffer) theory explains superconductivity based on weak electron-phonon interactions, but cuprate superconductors exhibit strong electron-electron correlations, making them difficult ...