Unscreened Coulomb interactions and quantum spin Hall phase in neutral zigzag graphene ribbons

Abstract

A study of the effect of unscreened Coulomb interactions on the quantum spin Hall (QSH) phase of finite-width neutral zigzag graphene ribbons is presented. By solving a tight-binding Hamiltonian that includes the intrinsic spin-orbit interaction (I-SO), exact expressions for band-structures and edge-states wavefunctions are obtained. These analytic results, supported by tight-binding calculations, show that chiral spin-filtered edge states are composed of localized and damped oscillatory wavefunctions, reminiscent of the ones obtained in armchair ribbons. The addition of long-range Coulomb interactions opens a gap in the charge sector with a gapless spin sector. In contrast to armchair terminations, the charge-gap vanishes exponentially with the ribbon width and its amplitude and decay-length are strongly dependent on the I-SO coupling. Comparison with reported ab-initio calculations are presented.

4 pages, 4 figures

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• Interacting two helical edge modes in quantum spin Hall systems
• Intrinsic spin-orbit interactions in flat and curved graphene nanoribbons
• Inverse quantum spin Hall effect generated by spin pumping from precessing magnetization into a graphene-based two-dimensional topological insulator
• Non-local exchange effects in zigzag edge magnetism of neutral graphene nanoribbons
• Effect of long-range interaction on graphene edge magnetism
• Quantum Spin Hall Effect in Graphene Nanoribbons: Effect of Edge Geometry
• Optimizing Topological Switching in Confined 2D-Xene Nanoribbons via Finite-Size Effects
• Kane-Mele Hubbard model on a zigzag ribbon: stability of the topological edge states and quantum phase transitions
• Charged Topological Solitons in Zigzag Graphene Nanoribbons
• Graphene zigzag ribbons, square lattice models and quantum spin chains
• Quantum spin Hall phase in neutral zigzag graphene ribbons
• Fate of gapless edge states in two-dimensional topological insulators with Hatsugai-Kohmoto interaction
• Rientrant metallicity in the Hubbard model: the case of honeycomb nanoribbons