Charge dynamics of doped holes in high Tc superconductors: a clue from one-hole optical conductivity in the t-J Holstein model

Nan Lin, Emanuel Gull, Andrew J. Millis

V. V. Kabanov, Alexei Vagov

Luca de’ Medici, Xin Wang, Massimo Capone +1 more

The three-band model relevant to high-temperature copper-oxide superconductors is solved using single-site dynamical mean field theory and a tight-binding parametrization of the copper and oxygen bands. For a band filling of one hole per unit cell the metal/charge-transfer-insulator phase diagram is determined. The electron spectral function, optical conductivity, and quasiparticle mass enhancement are computed as functions of electron and hole doping for parameters such that at one hole per cell the paramagnetic phase is insulating and for parameters such that at one hole per unit cell the paramagnetic phase is metallic. The optical conductivity is computed using the Peierls phase approximation for the optical matrix elements. The calculation includes the physics of ``Zhang-Rice singlets.'' The effects of antiferromagnetism on the magnitude of the gap and the relation between correlation strength and doping-induced changes in state density are determined. Three-band and one-band models are compared. The two models are found to yield quantitatively consistent results for all energies less than about 4 eV including energies in the vicinity of the charge-transfer gap. Parameters on the insulating side of the metal/charge-transfer insulator phase boundary lead to gaps which are too large and near-gap conductivities which are too small relative to data. The results place the cuprates clearly in the intermediate correlation regime, on the paramagnetic metal side of the metal/charge-transfer insulator phase boundary.

C. A. Balseiro, Alberto G. Rojo, Eduardo R. Gagliano +1 more

Michael Nakitare Waswa, John Wanjala Makokha

Determining the conduction mechanism that would raise the TC of cuprate high temperature superconductors remains a puzzle. Here, we modify the existing Bose-Fermi-Hubbard model, diagonalize it using Bogoliubov-Valatin Transformation in order to determine the Transitional temperature, TC of hole doped-( and & electron-doped-( and ) cuprates. Our model predicts enhanced TC values and hence it lays a very good platform in the study of high-TC superconductivity.

Dan Wulin, Hao Guo, Chih-Chun Chien +1 more