Non-Zhang-Rice singlet character of the first ionization state of T-CuO

TL;DR

This paper investigates the electronic structure of tetragonal CuO, revealing deviations from the Zhang-Rice singlet model and highlighting its potential to clarify longstanding issues in cuprate physics.

Contribution

It demonstrates that T-CuO exhibits non-Zhang-Rice singlet behavior, challenging previous one-band models and providing a new platform for testing cuprate theories.

Findings

Deviations from Zhang-Rice singlet in T-CuO

Magnetic frustration breaks $C_4$ symmetry

Consistent with ARPES data, contradicts one-band models

Abstract

We argue that tetragonal CuO (T-CuO) has the potential to finally settle long-standing modelling issues for cuprate physics. We compare the one-hole quasiparticle (qp) dispersion of T-CuO to that of cuprates, in the framework of the strongly-correlated ($U_{dd}\rightarrow \infty$) limit of the three-band Emery model. Unlike in CuO$_2$, magnetic frustration in T-CuO breaks the $C_4$ rotational symmetry and leads to strong deviations from the Zhang-Rice singlet picture in parts of the reciprocal space. Our results are consistent with angle-resolved photoemission spectroscopy data but in sharp contradiction to those of a one-band model previously suggested for them. These differences identify T-CuO as an ideal material to test a variety of scenarios proposed for explaining cuprate phenomenology.