Rare two-dimensional Dirac material

Summary of two-dimensional materials containing Dirac cones

Graphene (graphene) is a two-dimensional carbon material with a honeycomb-like atom structure and a single-layer atom thickness. Its discoveries not only break the long-standing predictions that the two-dimensional crystals are not stable in nature, but also make graphene extremely promising in both basic and applied research. In particular, the existence of the Dirac cone (Dirac cone) has given graphene many novel physical phenomena and electronic properties, such as semi-integers, fractional and fractal quantum Hall effects, ultra-high mobility, and so on.

Graphene's research opens the door to discovering more of the two-dimensional material. So far, hundreds of two-dimensional materials have been found, which includes the fourth main family of elements, the third and fifth main group of two compounds, metal sulfur compounds, composite oxides, and so on. However, only graphene, graphene (silicene), Germanium (germanene), some graphite acetylene (graphynes), and a few other systems are considered to be possible with the Dirac cone. Moreover, only the Dirac cone in graphene is really verified experimentally. So why are two-dimensional Dirac materials so scarce? What are the structural characteristics and properties of such materials? How to find and design a new Dirac system?

Around these issues, Dr. Wang Jinying, Dr. Dengshina, Liu Zhongfan academician and Liu Zhirong Associate professor of chemistry and molecular Engineering at Peking University jointly wrote a review of "rare two-dimensional Dirac material" and published it in the 1th issue of the National Science Review, 2015 (HTTP/ Nsr.oxfordjournals.org/content/2/1/22.full). This paper reviews the latest theoretical advances in a variety of two-dimensional Dirac materials, such as graphene, silicones, germanium, graphite acetylene, several boron tablets and carbon films, transition metal oxides (VO2) n/(TiO2) m and (CrO2) n/(TiO2) m, organic and organic metal crystals, So-mos2, and artificial lattice (electron gas and cold atom). In this paper, the structure and electron properties of these two-dimensional Dirac materials are introduced emphatically, the generation, movement and disappearance of Dirac points are expounded, and the scarcity of the two-dimensional Dirac system is explained by the relevant theory, and the existence of Dirac cone has a strict restriction on the symmetry, parameters, Fermi energy level and band coupling of the system. In order to find the new two-dimensional Dirac material provides the direction.

In recent years, Liu Zhongfan academician and Liu Zhirong Group have cooperated extensively on the theoretical research of graphene and other nanomaterials, and explored the energy band regulation, electronic transport properties, and chemical reaction of the materials in depth. Liu Zhongfan Group has developed a series of methods to control the growth and chemical modification of graphene, which realizes the partial regulation of graphene electronic properties. For example, they use the chemical vapor deposition method combined with a variety of material sources, the design of nitrogen doped, boron doped, and boron nitride hybrid graphene; the covalent modification of graphene was realized by chemical reaction, and the methods of photocatalytic paper-cut, photo-chlorination, photo-induced methylation and asymmetric covalent modification were developed. On the basis of experimental research, the electronic properties of graphene and other related nanomaterials have been studied theoretically and systematically by using the first principle calculation and tight-binding model of Liu Zhirong group. They explored the quantum limit domain, mechanical stress, chemical modification, and regional hybridization and other methods of graphene energy band structure and electronic transport properties of the Regulation, clarified the band gap regulation and migration rate changes in the intrinsic correlation, proposed the boron nitride hybrid graphene may be at the same time with a non-zero band gap and high mobility (up to 106 cm2 V-1 S-1) materials. In addition, they studied the graphite, carbon and other two-dimensional carbon materials, found the existence of Dirac cone and lattice symmetry close relationship, and designed a series of new two-dimensional Dirac material.

Source: Science Network http://news.sciencenet.cn/htmlpaper/2015481333774836141.shtm

Rare two-dimensional Dirac material