School of Physics and Optoelectronics, Xiangtan University , Xiangtan, Hunan 411105, China.
Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute , Troy, New York 12180, United States.
Nano Lett. 2015 Oct 14;15(10):6974-8. doi: 10.1021/acs.nanolett.5b02978. Epub 2015 Oct 5.
Carbon allotropes are subject of intense investigations for their superb structural, electronic, and chemical properties, but not for topological band properties because of the lack of strong spin-orbit coupling (SOC). Here, we show that conjugated p-orbital interactions, common to most carbon allotropes, can in principle produce a new type of topological band structure, forming the so-called Weyl-like semimetal in the absence of SOC. Taking a structurally stable interpenetrated graphene network (IGN) as example, we show, by first-principles calculations and tight-binding modeling, that its Fermi surface is made of two symmetry-protected Weyl-like loops with linear dispersion along perpendicular directions. These loops are reduced to Weyl-like points upon breaking of the inversion symmetry. Because of the topological properties of these band-structure anomalies, remarkably, at a surface terminated by vacuum there emerges a flat band in the loop case and two Fermi arcs in the point case. These topological carbon materials may also find applications in the fields of catalysts.
碳的同素异形体因其优异的结构、电子和化学性质而受到广泛关注，但由于缺乏强自旋轨道耦合（SOC），它们的拓扑能带性质并未得到研究。在这里，我们表明，大多数碳同素异形体中常见的共轭 p 轨道相互作用原则上可以产生一种新的拓扑能带结构，在没有 SOC 的情况下形成所谓的类 Weyl 半金属。以结构稳定的互穿石墨烯网络（IGN）为例，我们通过第一性原理计算和紧束缚模型表明，其费米面由两个具有垂直方向线性色散的对称保护类 Weyl 环组成。当反转对称性被破坏时，这些环简化为类 Weyl 点。由于这些带结构异常的拓扑性质，引人注目的是，在真空终止的表面上，在环的情况下出现一个扁平带，在点的情况下出现两个费米弧。这些拓扑碳材料也可能在催化剂领域得到应用。
