Single-particle spectra and magnetic susceptibility in the Emery model: a dynamical mean-field perspective

TL;DR

This study uses dynamical mean-field theory to analyze the Emery model for high-$T_c$ superconductors, revealing non-local correlations and oxygen-copper singlet fluctuations, but failing to reproduce pseudogap spectral features.

Contribution

It demonstrates that dynamical mean-field theory captures multi-orbital effects and magnetic susceptibility behavior in the Emery model, highlighting limitations in spectral property predictions.

Findings

Non-local correlations induce non-Curie susceptibility behavior.

Emerging oxygen-copper singlet fluctuations are observed.

Pseudogap spectral features are not captured by the theory.

Abstract

We investigate dynamical mean-field calculations of the three-band Emery model at the one- and two-particle level for material-realistic parameters of high-$T_c$ superconductors. Our study shows that even within dynamical mean-field theory, which accounts solely for temporal fluctuations, the intrinsic multi-orbital nature of the Emery model introduces effective non-local correlations. These correlations lead to a non-Curie-like temperature dependence of the magnetic susceptibility, consistent with nuclear magnetic resonance experiments in the pseudogap regime. By analyzing the temperature dependence of the uniform static spin susceptibility obtained by single-site and cluster dynamical mean-field theory, we find indications of emerging oxygen-copper singlet fluctuations, explicitly captured by the model. Despite correctly describing the hallmark of the pseudogap at the two-particle level, such as the drop in the Knight shift of nuclear magnetic resonance, dynamical mean-field theory fails to capture the spectral properties of the pseudogap.