M.M. Sánchez-López

Normal state quasiparticle structure in the high-Tc superconductors

Abstract We present a study of the normal state electronic structure of the high- T c superconductors obtained by diagonalizing the one-body Green function of the interacting system. Different approximations to the self-energy are considered. These corrections split the input density of state that is calculated within the local density formalism. The energy-dependent self-energy transfers part of spectral weight to the lower and upper Hubbard peaks, changing also the hole distribution in the different p and d states.

Renormalized electronic structures of CeSi2, CeRu2 and CeAl2

Abstract The renormalized density of states of some Ce compounds is analyzed by considering self-energy effects. We study the influence of the hybridization introduced by the self-energy and how it can affect the shape of the characteristic lower, upper and middle-energy resonance.

Mean-field and beyond mean-field effects on the electronic structure of YBa2Cu3O7

Abstract The electronic structure of YBa 2 Cu 3 O 7 is calculated by means of a method that operates for any self-energy approximation appropriated to strongly correlated systems. Working within the Hubbard picture, we consider mean-field and beyond mean-field approaches with two channels (p and d orbitals) for the localization. The band structure and the renormalized density of states are calculated and compared to available experimental data and theoretical results on YBa 2 Cu 3 O 7 . We find flat bands near the Fermi level, in agreement with angle-resolved photoemission spectra, and dispersion along k z of some bands. Our results show a multiple Hubbard splitting of the different p and d orbitals of the CuO 3 chains and the CuO 2 planes. This splitting leads to a redistribution of the density of holes on the oxygen sites and reasonably agrees with the characteristic disposition of bands of a charge-transfer system.

Hubbard's repulsion, self-energy and quasiparticles: Application to YBa2Cu3O7

Abstract The quasiparticle structure of YBa 2 Cu 3 O 7 is calculated within several approximations to the self-energy (RPA, ERPA, Hubbard I) and the model potential LDA+AMF. The partial DOS and distribution of holes yielded by the different approaches are presented and compared with available experimental data.

Superconductivity by charge and spin fluctuations in strongly correlated systems

Abstract We obtain the effective potential from a screened coulombian interaction considering separately the interaction between fermions with parallel and antiparallel spins. In both cases we analyze the possibility of obtaining superconductivity.

Electronic structure of CeSi2

We calculate the electronic structure of CeSi2 using an energy-dependent potential, added to the local density Hamiltonian, arising from an approximation to the self-energy corresponding to a multiband Hubbard Hamiltonian.

Self-Energy Effects in the Electronic Structure of Ce Systems: Application to CeSi2 and CeAl2

We calculate the electronic structure of CeSi2 and CeAl2 using an energy-dependent potential arising from an approximation to the self-energy corresponding to a multiband Hubbard Hamiltonian. This potential is added to the local-density Hamiltonian and we determine the renormalized density of states. This density of states displays different peaks centred about −2.5 eV, ±0.3 eV, and 4 eV with respect to EF, corresponding to the characteristic f features. We analyse these results and compare them with the previous data and theoretical interpretations of the electronic structure of these interesting materials.