Dirac topological insulator in the d(z)(2) manifold of a honeycomb oxide

作者：Lado J L^*; Pardo V

来源：Physical Review B, 2016, 94(11): 115141.

DOI：10.1103/PhysRevB.94.115141

We show by means of ab initio calculations and tight-binding modeling that an oxide system based on a honeycomb lattice can sustain topologically nontrivial states if a single orbital dominates the spectrum close to the Fermi level. In such a situation, the low-energy spectrum is described by two Dirac equations that become nontrivially gapped when spin-orbit coupling (SOC) is switched on. We provide one specific example but the recipe is general. We discuss a realization of this starting from a conventional spin-1/2 honeycomb antiferromagnet whose states close to the Fermi energy are d(z)(2) orbitals. Switching off magnetism by atomic substitution and ensuring that the electronic structure becomes two-dimensional is sufficient for topologicality to arise in such a system. By deriving a tight-bindingWannier Hamiltonian, we find that the gap in such a model scales linearly with SOC, opposed to other oxide-based topological insulators, where smaller gaps tend to appear by construction of the lattice. We showthat the quantum spin Hall state in this system survives in the presence of off-plane magnetism and the orbital magnetic field and we discuss its Landau level spectra, showing that our recipe provides a d(z)(2) realization of the Kane-Mele model.

• 出版日期2016-9-19