David Doennig1, Warren E. Pickett2 and Rossitza Pentcheva1

1Ludwig-Maximilians University, Munich, Germany

2Department of Physics, University of California at Davis, U.S.A.

Remarkably rich electronic behavior has been recently discovered in (001) oriented interfaces between LaAlO3 and SrTiO3 including two-dimensional conductivity, superconductivity and magnetism. However, 111 oriented superlattices promise to host exotic, possibly topologically nontrivial phases. Density functional theory calculations with an on-site Coulomb repulsion term (GGA+U method) reveal competing ground states in M LaAlO3/N SrTiO3(111) superlattices with n-type interfaces, ranging from spin, orbital polarized, Dirac point Fermi surface to charge ordered flat band phases. Orbital selectivity and metal-to-insulator transitions are steered by the interplay of Hubbard U, strain, and the SrTiO3 quantum well thickness. Under tensile strain inversion symmetry breaking drives the honeycomb lattice bilayer (N=2) from a ferromagnetic Dirac-point semimetal to a charge ordered flat band massive insulating phase [1]. An insulator-to-metal transition occurs with increasing SrTiO3 quantum well thickness.

Funding by the DFG SFB/TR80 and a grant for computational time at the Leibniz Rechenzentrum Garching are gratefully acknowledged.

 [1] D. Doennig, W.E. Pickett, and R. Pentcheva, condmat/1307.3516