Electronic structure of high-T c superconductors

Abstract

The band structure of doped high- T c superconductors (La 2− x Sr x CuO 4, etc.) is calculated. The mobile hole is considered in a ferromagnetic background of localized spins. Strong electron-electron Coulomb interaction as well as strong coupling with the excitons play an important role in the band formation. The charged quasiparticle in the x 2− y 2 band has spin S=0 with a small admixture of S=1 state. Close to the lowest x 2− y 2 band there is a z 2 band (Δ E≤1 eV) with S= 1 2 quasiparticle. Dependence of the frequency of the Cu nuclear quadrupole resonance (NQR) on x is considered.