Chemical control of orbital polarization in artificially structured transition-metal oxides: La2NiXO6 (X=B, Al, Ga, In) from first principles

TL;DR

This paper demonstrates that the choice of nontransition-metal counterion in LaNiO3/LaXO3 heterostructures can effectively control orbital polarization, offering a new method for designing correlated electron properties in oxide materials.

Contribution

It introduces a novel approach to orbital control in transition-metal oxides through atomic composition, expanding beyond strain and quantum confinement techniques.

Findings

Counterion X significantly influences orbital occupancy and polarization.

Density-functional calculations reveal changes in orbital polarization magnitude and sign.

Atomic composition can be used to tailor electronic properties in oxide heterostructures.

Abstract

The application of modern layer-by-layer growth techniques to transition-metal oxide materials raises the possibility of creating new classes of materials with rationally designed correlated electron properties. An important step toward this goal is the demonstration that electronic structure can be controlled by atomic composition. In compounds with partially occupied transition-metal d shells, one important aspect of the electronic structure is the relative occupancy of different d orbitals. Previous work has established that strain and quantum confinement can be used to influence orbital occupancy. In this paper we demonstrate a different modality for orbital control in transition-metal oxide heterostructures, using density-functional band calculations supplemented by a tight-binding analysis to show that the choice of nontransition-metal counterion X in transition-metal oxide heterostructures composed of alternating LaNiO3 and LaXO3 units strongly affects orbital occupancy, changing the magnitude and in some cases the sign of the orbital polarization.