Li Qiuyang, Yan Cuixia, Qi Chenchen, Qiu Shi, Yang Ting, Cai Jinming
Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, People's Republic of China.
Phys Chem Chem Phys. 2023 Apr 12;25(15):10811-10819. doi: 10.1039/d2cp05494a.
The fascinating Dirac cone, which has produced some excellent properties in graphene, such as ballistic charge transport, ultra-high carrier mobility and the quantum Hall effect, has motivated researchers to design and study more two dimensional (2D) Dirac materials. In this work, we have designed a family of 2D Dirac cone materials MX (M = Zn/Cd/Hg, X = Si/Ge) and studied their superior properties by first principles calculation. The calculated cohesive energy, phonon dispersion and molecular dynamics confirmed the energetic, dynamic and thermodynamic stability of ZnGe, CdGe, HgSi, and CdSi monolayers. It was found that the intrinsic Dirac cones exist in the electronic structure of the ZnGe, CdGe, HgSi and CdSi monolayers. Their Fermi velocities are from 3.26 × 10 m s to 4.32 × 10 m s (8.2 × 10 m s for graphene). It is noteworthy that the Dirac cone in the MX structure is robust. It is independent of external strain (from -7% to +19%) and can also be preserved as one-dimensional zigzag nanoribbons and multilayers (from two to three-layers). Our work shows that the novel MX Dirac cone materials are an important candidate for high-speed nanoelectronic devices.
在石墨烯中展现出诸如弹道电荷输运、超高载流子迁移率和量子霍尔效应等优异特性的迷人狄拉克锥，激发了研究人员去设计和研究更多的二维（2D）狄拉克材料。在这项工作中，我们设计了一族二维狄拉克锥材料MX（M = Zn/Cd/Hg，X = Si/Ge），并通过第一性原理计算研究了它们的优异特性。计算得到的结合能、声子色散和分子动力学证实了ZnGe、CdGe、HgSi和CdSi单层的能量、动力学和热力学稳定性。研究发现，ZnGe、CdGe、HgSi和CdSi单层的电子结构中存在本征狄拉克锥。它们的费米速度在3.26×10 m s至4.32×10 m s之间（石墨烯的费米速度为8.2×10 m s）。值得注意的是，MX结构中的狄拉克锥很稳定。它不受外部应变（从-7%到+19%）的影响，并且在一维锯齿形纳米带和多层结构（从两层到三层）中也能保持。我们的工作表明，新型MX狄拉克锥材料是高速纳米电子器件的重要候选材料。
