Antiferromagnetism and electronic structure of high-Tc cuprate

We solve a set of self-consistency equations for the three band Hubbard model of a CuO2 layer with the strong but finite Hubbard correlation, in presence of the antiferromagnetic (AF) order. The random phase approximation is applied to the electron propagators which contain the combined effect of both the Hubbard correlation and the hybridization between the nearest neighbor copper and oxygen orbitals. From the Green's functions, we can reproduce qualitatively correct behavior of the doping dependence of the AF order, and the Fermi surface which appears along with the carrier doping. Most important point to note in the result is that in the undoped materials the Fermi level lies in the antiferromagnetic gap, instead of in the charge transfer gap as generally believed. This differs from the common view that the undoped material is the charge transfer insulator and experimental results such as optical absorption. It agrees, however, with the recent experimental data obtained by the angle-resolved photoemission study by Marshall, et al. (Phys. Rev. Lett. 76, 4841 (1996)).