Electrons in High-Tc Compounds: Ab-Initio Correlation Results

TL;DR

This paper uses ab-initio methods to analyze electronic correlations in high-Tc compounds, comparing results with LDA, and explores doping effects and spin correlations relevant to magnetic properties.

Contribution

It introduces a detailed ab-initio approach to compute correlations and effective interactions in high-Tc compounds, revealing doping-dependent spin correlations not captured by simpler models.

Findings

Strong atomic correlations and spin correlations identified.

Nearest neighbor correlation is Stoner-enhanced and doping-dependent.

Calculated spin correlations agree qualitatively with neutron scattering data.

Abstract

Electronic correlations in the ground state of an idealized infinite-layer high-Tc compound are computed using the ab-initio method of local ansatz. Comparisons are made with the local-density approximation (LDA) results, and the correlation functions are analyzed in detail. These correlation functions are used to determine the effective atomic-interaction parameters for model Hamiltonians. On the resulting model, doping dependencies of the relevant correlations are investigated. Aside from the expected strong atomic correlations, particular spin correlations arise. The dominating contribution is a strong nearest neighbor correlation that is Stoner-enhanced due to the closeness of the ground state to the magnetic phase. This feature depends moderately on doping, and is absent in a single-band Hubbard model. Our calculated spin correlation function is in good qualitative agreement with that determined from the neutron scattering experiments for a metal.