Charge Imbalance Effects on Interlayer Hopping and Fermi Surfaces in Multilayered High-T_c Cuprates

We study doping dependence of interlayer hoppings, t_\perp, in multilayered cuprates with four or more CuO_2 planes in a unit cell. When the double occupancy is forbidden in the plane, an effective amplitude of t_\perp in the Gutzwiller approximation is shown to be proportional to the square root of the product of doping rates in adjacent two planes, i.e., t^eff_\perp \propto t_\perp \sqrt{\delta_1\delta_2}, where \delta_1 and \delta_2 represent the doping rates of the two planes. More than three-layered cuprates have two kinds of \cuo planes, i.e., inner- and outer planes (IP and OP), resulting in two different values of t^eff_{\perp}, i.e., t^eff_\perp 1 \propto t_\perp \sqrt{\delta_IP \delta_IP} between IP's, and t^eff_\perp 2 \propto t_\perp \sqrt{\delta_IP \delta_OP} between IP and OP. Fermi surfaces are calculated in the four-layered t-t'-t''-J model by the mean-field theory. The order parameters, the renormalization factor of t_\perp, and the site-potential making the charge imbalance between IP and OP are self-consistently determined for several doping rates. We show the interlayer splitting of the Fermi surfaces, which may be observed in the angle resolved photoemission spectroscopy measurement.Comment: Some typographical errors are revised. Journal of Physical Society of Japan, Vol.75, No.3, in pres

Parameters of the Effective Singlet-Triplet Model for Band Structure of High-TcT_c Cuprates by Different Approaches

The present paper covers the problem of parameters determination for High-$T_c$ superconductive copper oxides. Different approaches, {\it ab initio} LDA and LDA+U calculations and Generalized Tight-Binding (GTB) method for strongly correlated electron systems, are used to calculate hopping and exchange parameters of the effective singlet-triplet model for $CuO_2$-layer. The resulting parameters are in remarkably good agreement with each other and with parameters extracted from experiment. This set of parameters is proposed for proper quantitative description of physics of hole doped High-$T_c$ cuprates in the framework of effective models.Comment: PACS 74.72.h; 74.20.z; 74.25.Jb; 31.15.A