Highly Anisotropic Dirac Fermions in Square Graphynes

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• 作者：L. Z. Zhang ; Z. F. Wang ; Zhiming M. Wang ; S. X. Du ; H.-J. Gao ; Feng Liu
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2015
• 出版时间：August 6, 2015
• 年：2015
• 卷：6
• 期：15
• 页码：2959-2962
• 全文大小：354K
• ISSN：1948-7185

文摘

We predict a family of 2D carbon (C) allotropes, square graphynes (S-graphynes) that exhibit highly anisotropic Dirac fermions, using first-principle calculations within density functional theory. They have a square unit-cell containing two sizes of square C rings. The equal-energy contour of their 3D band structure shows a crescent shape, and the Dirac crescent has varying Fermi velocities from 0.6 脳 10⁵ to 7.2 脳 10⁵ m/s along different k directions. Near the Fermi level, the Dirac crescent can be nicely expressed by an extended 2D Dirac model Hamiltonian. Furthermore, tight-binding band fitting reveals that the Dirac crescent originates from the next-nearest-neighbor interactions between C atoms. S-graphynes may be used to build new 2D electronic devices taking advantages of their highly directional charge transport.