Dimensionality Control of d-orbital Occupation in Oxide Superlattices

Abstract

Manipulating the orbital state in a strongly correlated electron system is of fundamental and technological importance for exploring and developing novel electronic phases. Here, we report an unambiguous demonstration of orbital occupancy control between t2g and eg multiplets in quasi-twodimensional transition metal oxide superlattices (SLs) composed of a Mott insulator LaCoO3 and a band insulator LaAlO3. As the LaCoO3 sublayer thickness approaches its fundamental limit (i.e. one unit-cell-thick), the electronic state of the SLs changed from a Mott insulator, in which both t2g and eg orbitals are partially filled, to a band insulator by completely filling (emptying) the t2g (eg) orbitals. We found the reduction of dimensionality has a profound effect on the electronic structure evolution, which is, whereas, insensitive to the epitaxial strain. The remarkable orbital controllability shown here offers a promising pathway for novel applications such as catalysis and photovoltaics, where the energy of d level is an essential parameter.

References in corpus (10)

• The spin state transition in LaCoO${}_3$; revising a revision
• Orbital order and possible superconductivity in LaNiO3/LaMO3 superlattices
• Dimensionality Control of Electronic Phase Transitions in Nickel-Oxide Superlattices
• Orbital reflectometry
• Strain-Induced Spin States in Atomically Ordered Cobaltites
• Quantum confinement of Mott electrons in ultrathin LaNiO3/LaAlO3 superlattice
• Spin state transition and covalent bonding in LaCoO3
• Evolution of magnetic oxygen states in Sr-doped LaCoO${}_3$
• Two-Dimensional Confinement of 3d1 Electrons in LaTiO3/LaAlO3 Multilayers
• Doping Induced Spin State Transition in LaCoO3: Dynamical Mean-Field Study

Cited by in corpus (7)

• Correlated Quantum Phenomena of Spin-Orbit Coupled Perovskite Oxide Heterostructures: Cases of SrRuO3 and SrIrO3-Based Artificial Superlattices
• Strain-induced atomic-scale building blocks for ferromagnetism in epitaxial LaCoO3
• Tunable Ferromagnetism in LaCoO3 Epitaxial Thin Films
• Direct observation of double exchange in ferromagnetic La${}_{0.7}$Sr${}_{0.3}$CoO${}_3$ by broadband ellipsometry
• Photo-induced insulator-to-metal transition and coherent acoustic phonon propagation in LaCoO${}_3$ thin films explored by femtosecond pump-probe ellipsometry
• First-principles design of ferromagnetic monolayer MnO${}_2$ at the complex interface
• Optical signatures of strain-induced ferromagnetism in LaCoO${}_3$ thin film