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.

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Cited by in corpus (6)

• 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
• 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