Monolayer of the 5d transition metal trichloride OsCl3: A playground for two-dimensional magnetism, room-temperature quantum anomalous Hall effect, and topological phase transitions

Article

关键词: LOCALIZED WANNIER FUNCTIONS;    AUGMENTED-WAVE METHOD;    ELECTRONIC-STRUCTURE;    CORRELATED SYSTEMS;    XY MODEL;    INSULATORS;    SURFACE;   

DOI  :  10.1103/PhysRevB.95.201402

来源: SCIE

【 摘 要 】

Based on density functional theory (DFT) calculations, we predict that a monolayer of OsCl3 (which is 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 in-plane easy axis. The band gap opened by SOC is E-g similar or equal to 67 meV (or similar or equal to 191 meV if the easy axis can be tilted out of the plane by an external electric field), and the estimated Curie temperature of such an anisotropic planar rotator ferromagnet is T-C less than or similar to 350 K. The Chern number C = -1, generated by the manifold of Os t(2g) 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 5d electrons of Os exhibit both strong SOC and moderate correlation effects, we employ DFT+U calculations to show how increasing on-site Coulomb repulsion U: gradually reduces E-g while maintaining C = -1 for 0 < U < U-c, leads to a metallic phase with E-g = 0 at U-c, and opens a gap of topologically trivial Mott insulating phase with C = 0 for U > U-c.

【 授权许可】

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