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Non-equivalent nature of acetylenic bonds in typical square graphynes and intricate negative differential resistance
Subhadip Nath1, Niladri Sekhar Mondal2, Arka Bandyopadhyay3
1Department of Physics, Krishnagar Government College, Krishnagar 741101, India.
Abstract:
The role of acetylenic linkage in determining the exotic band structures of 4, 12, 2- and 4, 12, 4- graphynes is reported. The Dirac bands, as confirmed by both density functional theory and tight-binding calculations, are robust and stable over a wide range of hopping parameters betweensp-sp-hybridized carbon atoms. The shifting of the crossing points of the Dirac bands along thek-path of these two square graphynes is found to be in opposite direction with the hopping along with the acetylenic bond. A real space decimation scheme has also been adopted for understanding this interesting behavior of the band structure of these two graphynes. The condition for the appearance of a nodal ring in the band structure has been explored and critically tested by appropriate Boron-Nitrogen doping. Moreover, both the graphynes exhibit negative differential resistance in their current-voltage characteristics, with 4, 12, 2- graphynes showing superiority.
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