paper

Correlation-driven topological phase transition from in-plane magnetized quantum anomalous Hall to Mott insulating phase in monolayer transition metal trichlorides

arXiv:1610.02719 · doi:10.1103/PhysRevB.95.201402

Abstract

Based on density functional theory (DFT) calculations, we predict that a monolayer of OsCl---a layered material whose interlayer coupling is weaker than in graphite---possesses a quantum anomalous Hall (QAH) insulating phase generated by the combination of honeycomb lattice of osmium atoms, their strong spin-orbit coupling (SOC) and ferromagnetic ground state with {\em in-plane} easy-axis. The band gap opened by SOC is \mbox{ meV} (or \mbox{ meV} if the easy-axis can be tilted out of the plane by an external electric field), and the estimated Curie temperature of such {\em anisotropic planar rotator} ferromagnet is K. The Chern number , generated by the manifold of Os bands crossing the Fermi energy, signifies the presence of a single chiral edge state in nanoribbons of finite width, where we further show that edge states are spatially narrower for zigzag than armchair edges and investigate edge-state transport in the presence of vacancies at Os sites. Since electrons of Os exhibit {\em both} strong SOC and moderate correlation effects, we employ DFT+U calculations to show how increasing on-site Coulomb repulsion : gradually reduces while maintaining for ; leads to metallic phase with at ; and opens the gap of topologically trivial Mott insulating phase with for .

6 pages, 5 color PDF figures, PDFLaTeX

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