On the oxygen $p$ states in superconducting nickelates

TL;DR

This paper investigates the role of oxygen 2p states in superconducting nickelates using dynamical mean-field theory, revealing subtle charge-transfer effects and orbital characteristics that influence their electronic properties.

Contribution

It provides a detailed analysis of oxygen p states in nickelates, highlighting their subtle role near the Mott-Hubbard and charge-transfer boundary, which was less understood before.

Findings

Reduced doped holes on oxygen in nickelates

Asymmetry effects in infinite-layer nickelates

Bridging p_z orbitals in La3Ni2O7

Abstract

While key attention in transition-metal oxides is usually devoted to the $d$ states of the transition-metal ion, the O$(2p)$ states usually also carry important physics. We here examine these $p$ states in representatives of the novel superconducting nickelates, as described in realistic dynamical mean-field theory. Since the materials are located on the boundary between Mott-Hubbard and charge-transfer systems, the role of oxygen is expectedly subtle. Strong reduction of doped holes on oxygen and first asymmetry effects are featured in infinite-layer nickelates. A pronounced nature of bridging $p_z$ orbitals is identified in the La$_3$Ni$_2$O$_7$ system.