Graphene: Free electron scattering within an inverted honeycomb lattice

18 Aug 2018  ·  El-Fattah Z. M. Abd, Kher-Elden M. A., Piquero-Zulaica I., de Abajo F. J. Garcia, Ortega J. E. ·

Theoretical progress in graphene physics has largely relied on the application of a simple nearest-neighbor tight-binding model capable of predicting many of the electronic properties of this material. However, important features that include electron-hole asymmetry and the detailed electronic bands of basic graphene nanostructures (e.g., nanoribbons with different edge terminations) are beyond the capability of such simple model... Here we show that a similarly simple plane-wave solution for the one-electron states of an atom-based two-dimensional potential landscape, defined by a single fitting parameter (the scattering potential), performs better than the standard tight-binding model, and levels to density-functional theory in correctly reproducing the detailed band structure of a variety of graphene nanostructures. In particular, our approach identifies the three hierarchies of nonmetallic armchair nanoribbons, as well as the doubly-degenerate flat bands of free-standing zigzag nanoribbons with their energy splitting produced by symmetry breaking. The present simple plane-wave approach holds great potential for gaining insight into the electronic states and the electro-optical properties of graphene nanostructures and other two-dimensional materials with intact or gapped Dirac-like dispersions. read more

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Mesoscale and Nanoscale Physics Materials Science