Orbital correlations in bilayer nickelates: roles of doping and interlayer coupling

TL;DR

This study investigates how orbital correlations in bilayer nickelates are influenced by doping and interlayer coupling, using a minimal model to understand their role in stabilizing a weakly-insulating state observed experimentally.

Contribution

It provides a detailed analysis of the sensitivity of orbital correlations to various parameters, highlighting their potential role in the material's electronic state.

Findings

Orbital correlations are highly sensitive to interlayer coupling and doping levels.

Fermi surface modifications significantly affect orbital susceptibilities.

Orbital content and band structure details influence the insulating behavior.

Abstract

We study the nature of orbital correlations present in the bilayer nickelate within a minimal two-orbital tight-binding model to gain insights into their possible role in stabilizing the less-known weakly-insulating state. The latter has been observed experimentally at ambient pressure. In order to achieve this objective, we examine the static orbital susceptibilities within the random-phase approximation. Our study highlights the sensitivity of orbital correlations to various factors including the interlayer coupling, carrier concentration, band-structure details such as the orbital contents, the number of bands contributing at the Fermi level etc. We relate this sensitiveness to the modification of the Fermi surfaces as well as their orbital contents dependent on aforementioned factors.