Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 8: Low-Dimensional Systems: Oxide Hetero-Interfaces

TT 8.8: Vortrag

Montag, 16. März 2015, 11:30–11:45, H 3010

DFT+DMFT study of strain and interface effects in LaTiO₃ and LaVO₃ — Krzysztof Dymkowski, Gabriele Sclauzero, and •Claude Ederer — Materials Theory, ETH Zurich, Switzerland

Metal-insulator transitions in thin films of early transition metal correlated oxides are linked to both epitaxial strain and electronic reconstruction at the film/substrate interface. We separately address these two key factors for LaTiO₃ and LaVO₃ through density functional theory plus dynamical mean-field theory (DFT+DMFT). We find that mere epitaxial strain suffices to induce an insulator-to-metal transition in LaTiO₃ [1], but not in LaVO₃, in agreement with recent experiments [2]. We show that this difference can be explained by the combined effect of strain-induced changes in the crystal field splitting of t_2g orbitals and different orbital filling in these two materials. The role of the interface is investigated through DFT+DMFT simulations of LaVO₃/SrTiO₃ heterostructures with varying superlattice periodicities and substrate terminations. Our aim is to assess whether the metallicity observed at the LaVO3/SrTiO3 interface could be driven by pure electronic reconstruction effects, rather than structural or stoichiometric reasons (such as, e.g., O-related defects).

[1] Dymkowski/Ederer, Phys. Rev. B 89, 161109 (2014).

[2] He et al., Phys. Rev. B 86, 081401 (2012).