title: Line of Dirac Nodes in Hyperhoneycomb Lattices.
abstract: We propose a family of structures that have "Dirac loops," closed lines of Dirac nodes in momentum space, on which the density of states vanishes linearly with energy. Those lattices all possess the planar trigonal connectivity present in graphene, but are three dimensional. We show that their highly anisotropic and multiply connected Fermi surface leads to quantized Hall conductivities in three dimensions for magnetic fields with toroidal geometry. In the presence of spin-orbit coupling, we show that those structures have topological surface states. We discuss the feasibility of realizing the structures as new allotropes of carbon.
authors.affiliation: Department of Physics and Astronomy, University of Oklahoma, Norman, Oklahoma 73069, USA.
authors.forename: Kieran
authors.initials: K
authors.lastname: Mullen
authors.affiliation: Department of Physics and Astronomy, University of Oklahoma, Norman, Oklahoma 73069, USA.
authors.forename: Bruno
authors.initials: B
authors.lastname: Uchoa
authors.affiliation: Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73069, USA.
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Glatzhofer