Electronic structure of higher-order Ruddlesden-Popper nickelates

We analyze the electronic structure of the recently synthesized higher-order nickelate Ruddlesden-Popper phases La$_{n+1}$Ni$_n$O$_{3n+1}$ ($n=4-6$) using first-principles calculations. For all materials, our results show large holelike Fermi surfaces with $d_{x^2-y^2}$ character that closely resemble those of optimally hole-doped cuprates. For higher values of $n$, extra non-cuprate-like bands of $d_{z^2}$ orbital character appear. These aspects highlight that this Ruddlesden-Popper series can provide a means to modify the electronic ground states of nickelates by tuning their dimensionality. With their similarities and differences to the cuprates, this new family of materials can potentially shed light on the physics of copper-based oxides.