Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 47: Correlated Electrons: Other Materials

TT 47.8: Vortrag

Mittwoch, 9. März 2016, 12:30–12:45, H23

Breathing Mode Distortion and Magnetic Order in Rare-Earth Nickelates RNiO₃ — •Alexander Hampel and Claude Ederer — Materials Theory, ETH Zürich, Switzerland

Rare-earth nickelate perovskites display a rich and not yet fully understood phase diagram, where all RNiO₃ compounds with R from Sm to Lu undergo a non-magnetic metal-insulator transition (MIT). This transition is connected to a lattice distortion, which can be described as breathing mode of the oxygen octahedra surrounding the Ni cations. Between 100-250 K the RNiO₃ compounds undergo a magnetic transition to an antiferromagnetic (AFM) state, with a wave-vector k= [ 1/4 1/4 1/4 ] relative to the underlying simple cubic perovskite structure.
Here, we use density functional theory and its extensions (DFT+U, DFT+DMFT) together with distortion mode analysis to explore the interplay between lattice distortions, magnetic order, and the strength of the local Coulomb interaction U in rare earth nickelates. Our results show a strong dependency of the breathing mode amplitude on the magnetic order, with a much larger breathing mode obtained for the AFM state compared to the ferromagnetic case. Furthermore, we demonstrate that DFT+U is able to capture the correct trends of the lattice distortions across the nickelate series.