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arXiv · 1510.09177

Design of Mott and topological phases on buckled 3d-oxide honeycomb lattices

David Doennig·Santu Baidya·Warren E. Pickett·Rossitza Pentcheva
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Abstract

Perovskite bilayers with (111)-orientation combine a honeycomb lattice as a key feature with the strongly correlated, multiorbital nature of electrons in transition metal oxides. In a systematic DFT+$U$ study of (111)-oriented (La$X$O$_3$)$_2$/(LaAlO$_3$)$_4$ superlattices, we establish trends in the evolution of ground states versus band filling in (111)-oriented (La$X$O$_3$)$_2$/(LaAlO$_3$)$_4$ superlattices, with $X$ spanning the entire $3d$ transition metal series. The competition between local quasi-cubic and global triangular symmetry triggers unanticipated broken symmetry phases, with mechanisms ranging from Jahn-Teller distortions, to charge-, spin-, and orbital-ordering. LaMnO$_3$, where spin-orbit coupling opens a sizable gap in the Dirac-point Fermi surface, emerges as a topological Chern insulator.

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David Doennig, Santu Baidya, Warren E. Pickett, Rossitza Pentcheva. 2015-10-30. Design of Mott and topological phases on buckled 3d-oxide honeycomb lattices. https://doi.org/10.1103/physrevb.93.165145

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