Abstract
First-principles and semi-empirical tight binding calculations were performed to understand the adsorption of oxygen on the surface of two dimensional (2D) and zigzag stanene nano-ribbons. The intrinsic spin-orbit interaction is considered in the Kane-Mele tight binding model. The adsorption of an oxygen atom or molecule on the 2D stanene opens an electronic energy band gap. We investigate the helical edge states and topological phase in the pure zigzag stanene nano-ribbons. The adsorption of oxygen atoms on the zigzag stanene nano-ribbons deforms the helical edge states at the Fermi level which causes topological (non-trivial) to trivial phase transition. The structural stability of the systems is checked by performing Γ-point phonon calculations. Specific arrangements of adsorbed oxygen atoms on the surface of zigzag stanene nano-ribbons conserve the topological phase which has potential applications in future nano-electronic devices.
Highlights
IntroductionAfter the discovery of graphene,[1] other 2D nano-structures composed of group IV honeycomb lattices were theoretically proposed and synthesized.[2,3,4,5] Topological insulators were observed experimentally for 3D nano-structures[6,7,8,9] and predicted in low buckled 2D nano-structures.[10,11,12,13,14,15,16,17,18,19,20] The condition required for observing the Hall effect is to break the time-reversal invariance by applying a strong magnetic field
The stability of the adsorption of oxygen on the surface of 2D stanene is confirmed by performing Γ-point phonon calculations, see Fig. 2(a-b)
We present a study comprising density functional theory (DFT) and tight binding approaches to investigate the adsorption of oxygen on the 2D structure and zigzag stanene nano-ribbons
Summary
After the discovery of graphene,[1] other 2D nano-structures composed of group IV honeycomb lattices were theoretically proposed and synthesized.[2,3,4,5] Topological insulators were observed experimentally for 3D nano-structures[6,7,8,9] and predicted in low buckled 2D nano-structures.[10,11,12,13,14,15,16,17,18,19,20] The condition required for observing the Hall effect is to break the time-reversal invariance by applying a strong magnetic field. Kane and Mele modeled the intrinsic spin-orbit interaction (SOC) in 2D graphene and report a quantum Anomalous Hall effect for different spin directions which is called the quantum spin Hall effect or Z2 topological insulator.[13,21] Graphene is not an appropriate candidate for experimental realization of the quantum spin Hall effect because of a very weak intrinsic spinorbit interaction (10−3 meV).[22,23] By increasing the atomic mass using heavier atoms the intrinsic spin-orbit interaction strength is increased
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