Topological Bound States and Robust Electronic Transport in Bismuth-Modified Graphene Ribbons

International Journal of Physics | Vol. 8, No. 2, February 2017 | pp. 9–16

DOI: 10.46882/2017/IJP/000082

Research Article

Title: Topological Bound States and Robust Electronic Transport in Bismuth-Modified Graphene Ribbons

Names of Authors: J. W. Park¹, E. C. Vance²

Authors’ Affiliations: ¹Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon, South Korea; ²Department of Physics, University of California, Berkeley, California, USA

Abstract: Quantum spin Hall insulators provide an innovative pathway for developing low-power electronics by supporting backscattering-immune spin transport along their boundaries. This study designs and simulates topological bound states and robust spin transport within a two-dimensional honeycombed lattice of bismuth-modified graphene nanoribbons. We computed the electronic band structures using the relativistic tight-binding method across the Brillouin zone. The strong intrinsic spin-orbit coupling induced by bismuth atoms breaks the electronic degeneracy at the Dirac valleys, creating a bulk topological band gap with a width of 0.22 eV. We calculated a non-zero spin Chern number of Cs = +1, verifying the non-trivial topological character of the system. To demonstrate transport robustness, we simulated spin-polarized electron wavepacket propagation past single-atom vacancies and line defect boundaries. The edge mode bypassed these structural obstacles with a high transmission efficiency of 99.5% ± 0.2%, showing zero backscattering due to time-reversal symmetry protections. These findings provide solid engineering targets for building backscattering-immune spintronic transistors, quantum data pathways, and integrated spin-logic circuits.

Keywords: Topological insulators; quantum spin Hall effect; spin-orbit coupling; tight-binding method; edge states; spintronics

Manuscript Timeline: Received: November 05, 2016; Revised: December 18, 2016; Accepted: January 11, 2017; Published: February 15, 2017

Citation: Park, J. W., & Vance, E. C. (2017). Topological Bound States and Robust Electronic Transport in Bismuth-Modified Graphene Ribbons. International Journal of Physics, 8(2), 9–16.

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