Edge states of hydrogen terminated monolayer materials: silicene, germanene and stanene ribbons

Abstract

We investigate the energy dispersion of the edge states in zigzag silicene, germanene and stanene nanoribbons with and without hydrogen termination based on a multi-orbital tight-binding model. Since the low buckled structures are crucial for these materials, both the $\pi$ and $\sigma$ orbitals have a strong influence on the edge states, different from the case for graphene nanoribbons. The obtained dispersion of helical edge states is nonlinear, similar to that obtained by first-principles calculations. On the other hand, the dispersion derived from the single-orbital tight-binding model is always linear. Therefore, we find that the non-linearity comes from the multi-orbital effects, and accurate results cannot be obtained by the single-orbital model but can be obtained by the multi-orbital tight-binding model. We show that the multi-orbital model is essential for correctly understanding the dispersion of the edge states in tetragen nanoribbons with a low buckled geometry.

arXiv comment18 pages, 8 figures (including 8 online color figures)

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• Influence of edge magnetization and electric fields on zigzag silicene, germanene and stanene nanoribbons
• Emulating tightly bound electrons in crystalline solids using mechanical waves
• Valley- and Orbital-Controlled 2D Chern Insulators Without Spin-orbit Interaction