Apical oxygens and correlation strength in electron and hole doped copper oxides

TL;DR

This study compares electron and hole doped copper oxides using advanced theoretical methods, highlighting the role of apical oxygens in correlation strength and aligning theoretical predictions with experimental observations.

Contribution

It demonstrates how apical oxygens influence correlation strength and provides a detailed theoretical comparison of NCCO and LSCO, matching multiple experimental results.

Findings

NCCO's charge transfer gap is driven by magnetic order.

LSCO's gap is due to Mott physics.

Apical oxygens significantly affect correlation strength.

Abstract

We use the Local Density Approximation in combination with the Dynamical Mean Field Theory to carry out a comparative investigation of a typical electron doped and a typical hole doped copper oxide, NCCO and LSCO respectively. The parent compounds of both materials are strongly correlated electron systems in the vicinity of the metal to charge transfer insulator transition. In NCCO the magnetic long range order is essential to open a charge transfer gap, while Mott physics is responsible for the gap in LSCO. We highlights the role of the apical oxygens in determining the strength of the correlations and obtaining overall good agreement between theory and several experimentally determined quantities. Results for optical conductivity, polarized X-ray absorption and angle resolved photoemission are presented and compared with experiments.