We discuss the effects of interlayer hopping and the resulting kz-dispersion in the cuprates within the framework of the one-band tight binding (TB) model Hamiltonian. Specific forms of the dispersion relations in terms of the in-plane hopping parameters t, t ′ , t ′′ and t ′′′ and the effective interlayer hopping tz in La2−xSrxCuO4 (LSCO) and Nd2−xCexCuO4 (NCCO) and the added intracell hopping t bi between the CuO2 bilayers in Bi2Sr2CaCu2O8 (Bi2212) are presented. The values of the 'bare' parameters are obtained via fits with the first principles LDA-based band structures in LSCO, NCCO and Bi2212. The corresponding 'dressed' parameter sets which account for correlation effects beyond the LDA are derived by fitting experimental FS maps and dispersions near the Fermi energy in optimally doped and overdoped systems. The interlayer couplings tz and t bi are found generally to be a substantial fraction of the in-plane hopping t, although the value of tz in NCCO is anomalously small, reflecting absence of apical O atoms in the crystal structure. Our results provide some insight into the issues of the determination of doping from experimental FS maps in Bi2212, the role of intercell coupling in c-axis transport, and the possible correlations between the doping dependencies of the binding energies of the Van Hove singularities (VHSs) and various prominent features observed in the angle-resolved photoemission (ARPES) and tunneling spectra of the cuprates.
To date, angle-resolved photoemission spectroscopy has been successful in identifying energy scales of the many-body interactions in correlated materials, focused on binding energies of up to a few hundred meV below the Fermi energy. Here, at higher energy scale, we present improved experimental data from four families of high-Tc superconductors over a wide doping range that reveal a hierarchy of many-body interaction scales focused on: the low energy anomaly ("kink") of 0.03-0.09eV, a high energy anomaly of 0.3-0.5eV, and an anomalous enhancement of the width of the LDA-based CuO2 band extending to energies of ≈ 2 eV. Besides their universal behavior over the families, we find that all of these three dispersion anomalies also show clear doping dependence over the doping range presented.
We report the self-energy associated with RPA magnetic susceptibility in the
hole-doped Bi_2Sr_2CuO_6 (Bi2201) and the electron-doped Nd_{2-x}Ce_xCuO_4
(NCCO) in the overdoped regime within the framework of a one-band Hubbard
model. Strong weight is found in the magnetic spectrum around (pi, 0) at about
360 meV in Bi2201 and 640 meV in NCCO, which yields dispersion anomalies in
accord with the recently observed `waterfall' effects in the cuprates.Comment: Submitted to PRL, Dec. 21, 2006; 4 eps figures, revte
We carry out extensive first-principles doping-dependent computations of angle-resolved photoemission (ARPES) intensities in La2-xSrxCuO4 over a wide range of binding energies. Intercell hopping and the associated three dimensionality, which is usually neglected in discussing cuprate physics, is shown to play a key role in shaping the ARPES spectra. Despite the obvious importance of strong coupling effects (e.g., the presence of a lower Hubbard band coexisting with midgap states in the doped insulator), a number of salient features of the experimental ARPES spectra are captured to a surprising extent when kz dispersion is properly included in the analysis.
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