Optical Absorption in the Double-Layer Two-Dimensional Two-Band Model

A. Mishima

Chinese Journal of Physics

34卷2S期（1996 / 04 / 01）

347 - 351

英文

The optical properties are studied within the double-layer two-dimensional twoband model with the antiferromagnetic exchange interaction between nearest neighbor d and p spins. The optical absorption spectra ate computed within the mean-field theory with periodic boundary conditions. The insulating gap of about 1.7 eV appears for non-doping. The in-gap state appears at the absorption energy 0.5 eV for a single p hole. For two p holes, the Drude peak and the in-gap state appear at the absorption energy 0 eV and near 0.5 eV, respectively. The spectral intensity of the in-gap state increases for a single p hole, and those of the Drude peak and the in-gap state increase for two p holes, as the interlayer transfer energy increases. The two holes form a bound state to pairs. It turns out that the interlayer transfer energy is important such as the strong Coulomb repulsion, the dx^2-y^2, orbital, and the px and py orbitals in the electronic properties of high-T, copper oxides.