Topological doping of repulsive Hubbard models

TL;DR

This study investigates the spin configurations induced by holes in cuprates using the three-band Hubbard model, revealing metastable meron solutions and their dependence on interaction strength, with implications for understanding high-temperature superconductors.

Contribution

It introduces a detailed analysis of topological spin textures in the three-band Hubbard model, highlighting the conditions for meron stability and their relation to the one-band model.

Findings

Meron solutions are metastable and shift from site-centered to bond-centered with increased interaction.

Meron-antimeron solutions for hole pairs are unstable.

Hubbard interaction parameters must be carefully chosen to match the three-band model results.

Abstract

The spin configuration induced by single holes and hole pairs doped into stoichiometric, antiferromagnetic cuprates is considered. Unrestricted Hartree-Fock calculations for the three-band Hubbard model are employed to study spin-polaron and vortex-like (meron) solutions. Meron solutions for a single hole are found to be metastable with higher energy than spin polarons. We observe that the meron solution shifts from site-centered to bond-centered as the interaction is increased. Meron-antimeron solutions for hole pairs are found to be unstable. The results are in agreement with earlier findings for the one-band Hubbard model. However, we find that the Hubbard interaction of the one-band model has to be chosen similar to the one of the three-band model to obtain comparable results, not of the order of the charge-transfer gap, as previously expected.