Multilayer engineering of CaVO$_3$ thin films with SrTiO$_3$ and LaAlO$_3$ from DFT+DMFT

TL;DR

This study uses DFT+DMFT to explore how multilayer engineering affects the electronic properties of CaVO$_3$ thin films on different substrates, revealing significant interface effects and tunability of interfacial properties.

Contribution

It introduces a comparative analysis of interface effects in CaVO$_3$ thin films on SrTiO$_3$ and LaAlO$_3$, highlighting the impact of boundary conditions and multilayer design.

Findings

CaVO$_3$/SrTiO$_3$ interface has minimal effect, with strain causing insulating behavior.

CaVO$_3$/LaAlO$_3$ interface significantly alters properties depending on termination and boundary conditions.

Spectral properties vary from bulklike to highly doped phases, showing tunability through multilayer engineering.

Abstract

In this paper we use density functional theory combined with dynamical mean-field theory (DFT+DMFT) to study interface effects between thin films of the correlated metal CaVO$_3$ and the two typical substrate materials SrTiO$_3$ and LaAlO$_3$. We find that the CaVO$_3$/SrTiO$_3$ interface has only a marginal influence on the CaVO$_3$ thin film, with the dominant effect being the (bulklike) epitaxial strain imposed by the large lattice mismatch, rendering the CaVO$_3$ film insulating due to the enhanced orbital polarization related to the strong level splitting between the t$_{\mathrm{2g}}$ orbitals. In contrast, at the polar CaVO$_3$/LaAlO$_3$ interface, the presence of the interface can have a huge effect on the thin film properties, depending both on the specific interface termination as well as the specific boundary conditions imposed by the multilayer geometry. We compare three different approaches to model the interface between the correlated metal CaVO$_3$ and the band insulator LaAlO$_3$, which all impose a different set of (electrostatic) boundary conditions on the electronic structure. The spectral properties obtained from our calculations reveal a strong influence of the supercell geometry, ranging from bulklike to highly doped and structurally distorted phases, indicating a potential tunability of the interfacial properties via multilayer engineering.