Band mixing effects in one-dimensional charge transfer insulators

TL;DR

This study investigates how band mixing influences the electronic and magnetic properties of a one-dimensional model of charge transfer insulators, revealing insights across different regimes of charge transfer energy and Hubbard interaction.

Contribution

It provides a detailed analysis of spectral and spin properties in a 1D $pd$ system using DMRG, spanning from Mott insulators to negative charge transfer regimes, enhancing understanding of TMO physics.

Findings

Spectral functions vary significantly with charge transfer energy and U.

Identifies distinct features in x-ray absorption spectra across regimes.

Provides momentum-resolved insights into excited states in TMOs.

Abstract

The low-energy properties of transition metal oxides (TMOs) are governed by the electrons occupying strongly correlated $d$-orbitals that are hybridized with surrounding ligand oxygen $p$ orbitals to varying degrees. Their physics is thus established by a complex interplay between the transition-metal (TM)-ligand hopping $t$, charge transfer energy $\Delta_\mathrm{CT}$, and on-site TM Hubbard repulsion $U$. Here, we study the spectral properties of a one-dimensional (1D) analog of such a $pd$ system, with alternating TM $d$ and ligand anion $p$ orbitals situated along a chain. Using the density matrix renormalization group method, we study the model's single-particle spectral function, x-ray absorption spectrum, and dynamical spin structure factor as a function of $\Delta_\mathrm{CT}$ and $U$. In particular, we present results spanning from the Mott insulating ($\Delta_\mathrm{CT} > U$) to negative charge transfer regime $\Delta_\mathrm{CT} < 0$ to better understand the ground and momentum-resolved excited state properties of these different regimes. Our results can guide new studies on TMOs that seek to situate them within the Mott-Hubbard/charge transfer insulator classification scheme.