407 research outputs found
Predominance of the Kitaev interaction in a three-dimensional honeycomb iridate: from ab-initio to spin model
The recently discovered three-dimensional hyperhoneycomb iridate,
-LiIrO, has raised hopes for the realization of dominant Kitaev
interaction between spin-orbit entangled local moments due to its near-ideal
lattice structure. If true, this material may lie close to the sought-after
quantum spin liquid phase in three dimensions. Utilizing ab-initio electronic
structure calculations, we first show that the spin-orbit entangled basis,
=1/2, correctly captures the low energy electronic structure. The
effective spin model derived in the strong coupling limit supplemented by the
ab-initio results is shown to be dominated by the Kitaev interaction. We
demonstrated that the possible range of parameters is consistent with a
non-coplanar spiral magnetic order found in a recent experiment. All of these
analyses suggest that -LiIrO may be the closest among known
materials to the Kitaev spin liquid regime.Comment: 9 pages, 6 figures, 2 table
Topological Quantum Phase Transition in 5 Transition Metal Oxide NaIrO
We predict a quantum phase transition from normal to topological insulators
in the 5 transition metal oxide NaIrO, where the transition can be
driven by the change of the long-range hopping and trigonal crystal field
terms. From the first-principles-derived tight-binding Hamiltonian we determine
the phase boundary through the parity analysis. In addition, our
first-principles calculations for NaIrO model structures show that the
interlayer distance can be an important parameter for the existence of a
three-dimensional strong topological insulator phase. NaIrO is
suggested to be a candidate material which can have both a nontrivial topology
of bands and strong electron correlations
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