Influence of quantum confinement and strain on orbital polarization of four-layer LaNiO${}_3$ superlattices: a DFT+DMFT study

Abstract

Atomically precise superlattices involving transition metal oxides provide a unique opportunity to engineer correlated electron physics using strain (modulated by choice of substate) and quantum confinement (controlled by layer thickness). Here we use the combination of density functional theory and dynamical mean field theory (DFT+DMFT) to study Ni E${}_g$ $d$-orbital polarization in strained LaNiO${}_3$/LaAlO${}_3$ superlattices consisting of four layers of nominally metallic NiO${}_2$ and four layers of insulating AlO${}_2$ separated by LaO layers. The layer-resolved orbital polarization is calculated as a function of strain and analyzed in terms of structural, quantum confinement, and correlation effects. The effect of strain is determined from the dependence of the results on the Ni-O bond-length ratio and the octahedral rotation angles; quantum confinement is studied by comparison to bulk calculations with similar degrees of strain; correlation effects are inferred by varying interaction parameters within our DFT+DMFT calculations. The calculated dependence of orbital polarization on strain in superlattices is qualitatively consistent with recent X-ray absorption spectroscopy and resonant reflectometry data. However, interesting differences of detail are found between theory and experiment. Under tensile strain, the two inequivalent Ni ions display orbital polarization similar to that calculated for strained bulk LaNiO${}_3$ and observed in experiment. Compressive strain produces a larger dependence of orbital polarization on Ni position and even the inner Ni layer exhibits orbital polarization different from that calculated for strained bulk LaNiO${}_3$.

9 pages, 6 figures

References in corpus (9)

• Quantum Monte Carlo Impurity Solver for Cluster DMFT and Electronic Structure Calculations in Adjustable Base
• Hybridization expansion impurity solver: General formulation and application to Kondo lattice and two-orbital models
• Orbital order and possible superconductivity in LaNiO3/LaMO3 superlattices
• Emergent properties hidden in plane view: Strong electronic correlations at oxide interfaces
• Computing total energies in complex materials using charge self-consistent DFT+DMFT
• Chemical control of orbital polarization in artificially structured transition-metal oxides: La2NiXO6 (X=B, Al, Ga, In) from first principles
• Orbital Polarization in Strained LaNiO${}_3$: Structural Distortions and Correlation Effects
• Quantifying electronic correlation strength in a complex oxide: a combined DMFT and ARPES study of LaNiO${}_3$
• Strain Control of Electronic Phase in Rare Earth Nickelates

Cited by in corpus (9)

• Nature of the metal-insulator transition in few-unit-cell-thick LaNiO3 films
• Disentangling lattice and electronic contributions to the metal-insulator transition from bulk vs. layer confined RNiO${}_3$
• Confinement- and strain-induced enhancement of thermoelectric properties in LaNiO${}_3$/LaAlO${}_3(001)$ superlattices
• Orbital engineering in nickelate heterostructures driven by anisotropic oxygen hybridization rather than orbital energy levels
• Inducing $n$- and $p$-type thermoelectricity in oxide superlattices by strain tuning of orbital-selective transport resonances
• Oxygen vacancy formation and electronic reconstruction in strained LaNiO${}_3$ and LaNiO${}_3$/LaAlO${}_3$ superlattices
• Finite-temperature phase diagram of (111) nickelate bilayers
• Epitaxially strained ultrathin LaNiO${}_3$/LaAlO${}_3$ and LaNiO${}_3$/SrTiO${}_3$ superlattices: a density functional theory + $U$ study
• Energy Landscape analysis of metal-insulator transitions: theory and application to Ca${}_2$RuO${}_4$, $R$NiO${}_3$ and their heterostructures