title: Nanostructured Carbon Allotropes with Weyl-like Loops and Points.
abstract: 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.
authors.affiliation: 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.
authors.forename: Yuanping
authors.initials: Y
authors.lastname: Chen
authors.affiliation: School of Physics and Optoelectronics, Xiangtan University , Xiangtan, Hunan 411105, China.
authors.forename: Yuee
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Research Laboratory for Quantum Materials and EPD Pillar, Singapore University of Technology and Design , Singapore 487372, Singapore.
authors.forename: Shengyuan A
authors.initials: SA
authors.lastname: Yang
authors.affiliation: Department of Physics, Beihang University , Beijing 100191, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Pan
authors.affiliation: Department of Physics, University of Texas at Dallas , Richardson, Texas 75080, United States.
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.affiliation: Department of Physics, University of California at Berkeley, and Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Marvin L
authors.initials: ML
authors.lastname: Cohen
authors.affiliation: Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute , Troy, New York 12180, United States.
authors.forename: Shengbai
authors.initials: S
authors.lastname: Zhang
keywords: Graphene network; Weyl semimetal; Weyl-like loops; Weyl-like points; flat surface band; surface Fermi arc