Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 94: Low-Dimensional Systems: Oxide Hetero-Interfaces

TT 94.10: Talk

Thursday, April 3, 2014, 17:30–17:45, HSZ 204

DFT+DMFT study of epitaxially strained LaVO₃ — •Gabriele Sclauzero, Krzysztof Dymkowski, and Claude Ederer — Materials Theory, ETH Zurich, Switzerland

LaVO₃ is a t_2g perovskite showing a rich phase diagram as a function of temperature, with a paramagnetic Mott-Hubbard insulating state at room temperature. Recently, it has become possible to produce and characterize strained lattices of LaVO₃ in thin films and superlattices of high structural quality. In such heterostructures both interface effects and epitaxial strain play an important role in the electronic reconstruction of the material, and it is often difficult to distinguish between these two effects in experiments. Moreover, the epitaxial strain can induce at least two different important modifications of the atomic geometry, namely: (i) a change in the amplitudes of the VO₆ octahedral rotations; (ii) a stretching or compression of V–O bonds.

In this work, we perform density functional theory plus dynamical mean field theory (DFT+DMFT) simulations to study how the correlated Mott-Hubbard phase of LaVO₃ is affected by epitaxial strain. We separate the effect of bond-length changes from that of octahedral rotations by comparing an idealized structure without rotations and a realistic one derived from the bulk orthorhombic phase. We interpret our findings through the strain-induced changes in the energies of the crystal-field t_2g levels of the local DFT Hamiltonian and in the occupation matrix obtained from DMFT. A comparison with the t_2g perovskite LaTiO₃, which shows an insulator-to-metal transition upon compressive strain, will also be presented.