title: Dirac Fermions in Borophene.
abstract: Honeycomb structures of group IV elements can host massless Dirac fermions with nontrivial Berry phases. Their potential for electronic applications has attracted great interest and spurred a broad search for new Dirac materials especially in monolayer structures. We present a detailed investigation of the β_{12} sheet, which is a borophene structure that can form spontaneously on a Ag(111) surface. Our tight-binding analysis revealed that the lattice of the β_{12} sheet could be decomposed into two triangular sublattices in a way similar to that for a honeycomb lattice, thereby hosting Dirac cones. Furthermore, each Dirac cone could be split by introducing periodic perturbations representing overlayer-substrate interactions. These unusual electronic structures were confirmed by angle-resolved photoemission spectroscopy and validated by first-principles calculations. Our results suggest monolayer boron as a new platform for realizing novel high-speed low-dissipation devices.
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Baojie
authors.initials: B
authors.lastname: Feng
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Sugino
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Ro-Ya
authors.initials: RY
authors.lastname: Liu
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan.
authors.forename: Ryu
authors.initials: R
authors.lastname: Yukawa
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Kawamura
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Takushi
authors.initials: T
authors.lastname: Iimori
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Howon
authors.initials: H
authors.lastname: Kim
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Hasegawa
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Lan
authors.initials: L
authors.lastname: Chen
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.|Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
authors.forename: Kehui
authors.initials: K
authors.lastname: Wu
authors.affiliation: Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kumigashira
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Komori
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.|Department of Physics, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: Tai-Chang
authors.initials: TC
authors.lastname: Chiang
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.|Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Meng
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Iwao
authors.initials: I
authors.lastname: Matsuda