Electronic structure and magnetic properties of higher-order layered nickelates: La$_{n+1}$Ni$_{n}$O$_{2n+2}$ ($n=4-6$)

TL;DR

This study uses first-principles calculations to explore the electronic and magnetic properties of higher-order layered nickelates (n=4-6), revealing increased cuprate-like behavior as the layer number decreases, which informs potential high-temperature superconductor development.

Contribution

It provides the first theoretical analysis of hypothetical n=4, 5, 6 layered nickelates, comparing their properties with known members and revealing trends in cuprate-like characteristics.

Findings

Cuprate-like character increases from n=∞ to n=3.

Charge transfer energy decreases with lower n.

Self-doping effects diminish as n decreases.

Abstract

The recent discovery of superconductivity in Sr-doped NdNiO$_2$, with a critical temperature of $10-15$ K suggests the possibility of a new family of nickel-based high-temperature superconductors (HTS). NdNiO$_{2}$ is the $n=\infty$ member of a larger series of layered nickelates with chemical formula R$_{n+1}$Ni$_{n}$O$_{2n+2}$ (R $=$ La, Nd, Pr; $n = 2, 3, \dots, \infty$). The $n=3$ member has been experimentally and theoretically shown to be cuprate-like and a promising HTS candidate if electron doping could be achieved. The higher-order $n=4,5,$ and $6$ members of the series fall directly into the cuprate dome area of filling without the need of doping, thus making them promising materials to study, but have not been synthesized yet. Here, we perform first-principles calculations on hypothetical $n=4,5,$ and $6$ structures to study their electronic and magnetic properties and compare them with the known $n=\infty$ and $n=3$ materials. From our calculations, we find that the cuprate-like character of layered nickelates increases from the $n=\infty$ to the $n=3$ members as the charge transfer energy and the self-doping effect due to R-$d$ bands around the Fermi level gradually decrease.