Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

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

TT 94.8: Talk

Thursday, April 3, 2014, 17:00–17:15, HSZ 204

Confinement-driven electronic phases in
(LaAlO₃)_M/(LaNiO₃)_N(111) superlattices — •David Doennig and Rossitza Pentcheva — Ludwig-Maximilians University Munich

Complex oxide heterostructures exhibit a broad variability of functional properties and electronic states, not available in the bulk. Beyond the much studied (001)-oriented systems, here we highlight theoretical results on (111) perovskite superlattices (SLs) containing the correlated metal LaNiO₃ (LNO) and the band insulator LaAlO₃ (LAO). Density functional theory calculations with an on-site Coulomb repulsion term reveal a rich spectrum of electronic phases in (LAO)_M/(LNO)_N(111) SLs as a function of the LNO and LAO thickness N and M in the superlattice. In the double perovskite 1/1 system, a Jahn-Teller distortion with d_z² orbital polarization leads to a ferromagnetic Mott insulating phase, so far unanticipated for nickelates. For the LNO bilayer (N=2) with graphene topology, a Dirac-point Fermi surface is obtained, while symmetry breaking leads to band gap opening with two inequivalent interfaces. For N≥ 3 the confined LNO slab undergoes a metal-to-insulator transition to a half-semimetallic phase with conduction originating from the interfaces. Antiferromagnetic arrangements allow combining motifs of the bilayer and single trigonal layer band structures in engineered artificial mixed phases. We acknowledge funding by the DFG, SFB/TR80.