Carrier location in high-Tc superconductors and the degree of cu-o covalency

E. B. Stechel; D. R. Jennison

doi:10.1103/PhysRevB.38.8873

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Carrier location in high-Tc superconductors and the degree of cu-o covalency

E. B. Stechel, D. R. Jennison

DOI 10.1103/PhysRevB.38.8873 · Physical Review B

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Abstract

We exactly solve a realistic three-band extended Hubbard model for the ground and low-lying excited states of a variety of finite clusters representing CuO2 sheets. Because the virtual state involving the copper d10 valence fluctuation has its energy sharply lowered by the presence of a carrier hole, a strong stabilization results if the carrier holes are in oxygen orbitals that are strongly coupled to the copper sites: For example, in spite of strong correlation, at carrier densities of interest and with a reasonable choice of energy parameters, the carrier hole wave function is dominated by the pσ orbital, rather than by the pπ orbital which is favored by the Madelung potential. Our previous conclusions concerning the carrier quasiparticles are supported by these calculations.