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

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, bandstructure 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 the aforementioned factors.