Highly Anisotropic Dirac Fermions in Square Graphynes.
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 × 10(5) to 7.2 × 10(5) 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.
†Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China.|‡Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.|§Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, United States.
L Z
LZ
Zhang
§Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, United States.|⊥Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China.
Z F
ZF
Wang
†Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China.
Zhiming M
ZM
Wang
‡Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
S X
SX
Du
‡Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
H-J
HJ
Gao
§Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, United States.|∥Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
Feng
F
Liu
Anisotropic Dirac Fermions; first-principles calculations; graphyne; two-dimensional material