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TT: Fachverband Tiefe Temperaturen

TT 24: Magnetic Heuslers, Half-Metals and Oxides II (organized by MA)

TT 24.1: Invited Talk

Monday, March 31, 2014, 15:00–15:30, BEY 118

Design principles of Dirac fermions and Mott insulating states in (111) oriented perovskite superlattices — •Rossitza Pentcheva — Ludwig Maximilians University, Munich, Germany

Oxide interfaces exhibit a broad spectrum of functional properties that are not available in the respective bulk compounds, such as two-dimensional conductivity, superconductivity and magnetism. With their distinct topology, (111) perovskite superlattices promise to host even more exotic electronic states compared to the much studied (001)-oriented systems. Material-specific density functional theory calculations with an on-site Coulomb repulsion term are used to explore the role of confinement, symmetry breaking, polarity mismatch and strain in the emergence of novel phases. The results illuminate a rich set of competing ground states in (LaAlO₃)_M/(SrTiO₃)_N(111) [1] and (LaNiO₃)_N/ (LaAlO₃)_M(111) superlattices, ranging from spin-polarized, Dirac-point Fermi surfaces to charge-ordered Mott or Peierls insulating phases. Orbital reconstructions and metal-to-insulator transitions depend critically on the thickness of the quantum well N and in-plane strain, thus opening avenues for engineering properties at the nanoscale. Research in collaboration with D. Doennig and W.E. Pickett, supported by the DFG, SFB/TR80. [1] D. Doennig, W. E. Pickett, and R. Pentcheva, Phys. Rev. Lett. 111 126804 (2013).