  We use the variational mean-field approach to systematically study the phase
diagram of a bilayer heterostructure of the correlated transition metal oxide
LaNiO3, grown along the (111) direction. The Ni 3+ ions with d7 (or eg1)
configuration form a buckled honeycomb lattice. We show that as a function of
the strength of the on-site interactions, various topological phases emerge. In
the presence of a reasonable size of the Hund's coupling, as the correlation is
tuned from intermediate to strong, the following sequence of phases is found:
(1) a Dirac half-semimetal phase, (2) a quantum anomalous hall insulator (QAHI)
phase with Chern number one, and (3) a ferromagnetic nematic phase breaking the
lattice point group symmetry. The spin-orbit couplings and magnetism are both
dynamically generated in the QAHI phase.
