Massive Symmetry Breaking in LaAlO3/SrTiO3(111) Quantum Wells: A Three-Orbital Strongly Correlated Generalization of Graphene

David Doennig, Warren E. Pickett, and Rossitza Pentcheva
Phys. Rev. Lett. 111, 126804 – Published 19 September 2013
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Abstract

Density functional theory calculations with an on-site Coulomb repulsion term reveal competing ground states in (111)-oriented (LaAlO3)M/(SrTiO3)N superlattices with n-type interfaces, ranging from spin, orbitally polarized (with selective eg, a1g, or dxy occupation), Dirac point Fermi surface, to charge-ordered flat band phases. These phases are steered by the interplay of (i) Hubbard U, (ii) SrTiO3 quantum well thickness, and (iii) crystal field splitting tied to in-plane strain. In the honeycomb lattice bilayer N=2 under tensile strain, inversion symmetry breaking drives the system from a ferromagnetic Dirac point (massless Weyl semimetal) to a charge-ordered multiferroic (ferromagnetic and ferroelectric) flat band massive (insulating) phase. With increasing SrTiO3 quantum well thickness an insulator-to-metal transition occurs.

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  • Received 29 March 2013

DOI:https://doi.org/10.1103/PhysRevLett.111.126804

© 2013 American Physical Society

Authors & Affiliations

David Doennig1, Warren E. Pickett2, and Rossitza Pentcheva1,*

  • 1Department of Earth and Environmental Sciences, Section Crystallography and Center of Nanoscience, University of Munich, Theresienstrasse 41, 80333 Munich, Germany
  • 2Department of Physics, University of California Davis, One Shields Avenue, Davis, California 95616, USA

  • *rossitzap@lmu.de

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Vol. 111, Iss. 12 — 20 September 2013

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