Electronic properties of high-Tcsuperconductors

Abstract

We study a generalized Hubbard Hamiltonian which includes the Cu and O orbitals in the ${\mathrm{CuO}}_2$ planes of high-$T_c$ superconductors. We use slave-boson technique to account for the intra- and interatomic correlations. In the saddle-point approximation we obtain the metal-insulator phase diagram and conclude that, for one hole per unit cell in the ${\mathrm{CuO}}_2$ plane, ${\mathrm{La}}_2$ ${\mathrm{CuO}}_4$ is a charge-transfer insulator. Our results show that doping produces a rapid metallization of the system and destroys antiferromagnetic order. Transport properties and mechanism for superconductivity are briefly discussed.