Electronic structure and orbital polarization of LaNiO$_3$ with a reduced coordination and under strain: first-principles study

TL;DR

This study uses first-principles calculations to explore how reduced coordination and strain affect the electronic structure and orbital polarization of LaNiO$_3$, revealing enhanced $d_{3z^2-r^2}$ orbital occupation and strain-independent polarization sign.

Contribution

It provides new insights into the orbital polarization behavior of LaNiO$_3$ with reduced coordination and under strain through first-principles simulations.

Findings

Enhanced $d_{3z^2-r^2}$ orbital occupation due to reduced coordination.

Orbital polarization sign remains unchanged under external strain.

Comparison with bulk and heterostructure cases clarifies experimental observations.

Abstract

First-principles density functional theory calculations have been performed to understand the electronic structure and orbital polarization of LaNiO$_3$ with a reduced coordination and under strain. From the slab calculation to simulate [001] surface, it is found that $d_{3z^2-r^2}$ orbital occupation is significantly enhanced relative to $d_{x^2-y^2}$ occupation owing to the reduced coordination along the perpendicular direction to the sample plane. Furthermore, the sign of the orbital polarization does not change under external strain. The results are discussed in comparison to the bulk and heterostructure cases, which sheds new light on the understanding of the available experimental data.