Tight-binding Hamiltonians for high-temperature superconductors and applications to coherent-potential-approximation calculations of the electronic properties of La2−xBaxCuO4−y

Abstract

We present accurate tight-binding parametrizations of the first-principles augmented-plane-wave or linear-augmented-plane-wave band structures of LaCuO3, La2CuO4, Ba2CuO4, and the high-temperature superconductor YBa2Cu3O7. We discuss the methodology and efficient application of these fits, including as an example our tight-binding coherent-potential-approximation (CPA) calculations of the effects of disorder on the electronic structure of La2−xBaxCuO4−y. Our CPA calculations support the hypothesis of a rigid-band lowering of the Fermi level for La2−xBaxCuO4, enhancing the density of states there. However, for La2BaCuO4−y they yield the interesting result that oxygen vacancies also lower EF and raise N(EF). This is a significant result for the theory of superconductivity in these materials. In addition to CPA calculations, our parametrizations of the band structures should prove to be a useful tool for other studies which will enhance our understanding of these materials.

Source-reported materials — not catalogue approval

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