Coupling angle resolved photoemission data and quasiparticle structure in antiferromagnetic insulators Sr2CuO2Cl2 and Ca2CuO2Cl2

We have analyzed the quasiparticle dispersion and ARPES-spectral density for Sr2CuO2Cl2 and Ca2CuO2Cl2 antiferromagnetic insulators along basic symmetric directions of the Brillouin zone (BZ) in a framework of an extended tight binding method (ETBM) with explicit account for intracell strong electron correlations. The quasiparticle dispersion is in a good agreement with ARPES- data. At the top of valence band we found a narrow impurity-like virtual level with the spectral weight proportional to the concentration of spin fluctuations. A pseudogap between the virtual level and the top of the valence band has dispersion similar to 'remnant Fermi surface' in Ca2CuO2Cl2 and to a pseudogap in the underdoped Bi2212 samples. A calculated parity of the polarized ARPES-spectra in (0,0),(pi/2,pi/2),(pi,0) - points in the AFM- phase is even with regard to relative magnitudes of the partial contributions by different orbitals to the total ARPES- spectral density. Conditions of an observability for the different partial contributions in the polarized ARPES- experiments are determined also.Comment: 15 pdf-pages with 10 figures and tabl

Spin fluctuations influence on quasiparticle spectrum of realistic p-d model

In the present work the multiband p-d model for $CuO_2$-layer is treated. It was shown that for the realistic set of parameters besides Zhang-Rice two-particle singlet there is non-negligible contribution of two-particle triplet state to the top of the valence band. Also shown, that to gain quantitative agreement with experimental data the minimal approximation should include the spin fluctuations beyond the Hubbard-I scheme. Quasiparticle spectrum, obtained in this approximation, is in fairly good agreement with ARPES data on Bi2212 High-$T_c$ compound.Comment: Submitted to ICM 2003 Conference 3 pages, 2 figure

Possible propagation of the Zhang-Rice singlet as a probable Cooper channel in the CuO2CuO_2 planes

The issue of how superconductivity originate in the $CuO_2$ planes believed to be crucial to understanding the high $T_c$ superconducting cuprates is still an going debate. In the wake of recent experimental observations of the the Zhang-Rice singlet (ZRS), its formation and propagation need to be revisited especially by using a simple approach almost at a phenomenological level. Within a highly simplified correlated variational approach (HSCVA) in this paper, a new formation of the ZRS as constituting the ground state of a single-band t-J model of the $CuO_2$ planes is developed. This formation is then used to demonstrate how the ZRS can be propagated as a probable Cooper channel in the $CuO_2$ planes.Comment: 10 page