151 research outputs found
A -matrix generalization of the Kitaev model
We extend the Kitaev model defined for the Pauli-matrices to the Clifford
algebra of -matrices, taking the representation as an
example. On a decorated square lattice, the ground state spontaneously breaks
time-reversal symmetry and exhibits a topological phase transition. The
topologically non-trivial phase carries gapless chiral edge modes along the
sample boundary. On the 3D diamond lattice, the ground states can exhibit
gapless 3D Dirac cone-like excitations and gapped topological insulating
states. Generalizations to even higher rank -matrices are also
discussed.Comment: A revised versio
A comparative DMFT study of the eg-orbital Hubbard model in thin films
Heterostructures of transition-metal oxides emerged as a new route to
engineer electronic systems with desired functionalities. Motivated by these
developments, we study a two-orbital Hubbard model in a thin-film geometry
confined along the cubic [001] direction using the dynamical mean-field theory.
We contrast the results of two approximate impurity solvers (exact
diagonalization and one-crossing approximation) to the results of the
numerically exact continuous-time quantum Monte Carlo solver. Consistent with
earlier studies, we find that the one-crossing approximation performs well in
the insulating regime, while the advantage of the exact-diagonalization based
solver is more pronounced in the metallic regime. We then investigate various
aspects of strongly correlated eg-orbital systems in thin film geometries. In
particular, we show how the interfacial orbital polarization dies off quickly a
few layers from the interface and how the film thickness affects the location
of the interaction-driven Mott transition. In addition, we explore the changes
in the electronic structure with varying carrier concentration and identify
large variations of the orbital polarization in the strongly correlated regime.Comment: 11 pages, 11 figure
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