title: A stable three-dimensional topological Dirac semimetal Cd3As2.
abstract: Three-dimensional (3D) topological Dirac semimetals (TDSs) are a recently proposed state of quantum matter that have attracted increasing attention in physics and materials science. A 3D TDS is not only a bulk analogue of graphene; it also exhibits non-trivial topology in its electronic structure that shares similarities with topological insulators. Moreover, a TDS can potentially be driven into other exotic phases (such as Weyl semimetals, axion insulators and topological superconductors), making it a unique parent compound for the study of these states and the phase transitions between them. Here, by performing angle-resolved photoemission spectroscopy, we directly observe a pair of 3D Dirac fermions in Cd3As2, proving that it is a model 3D TDS. Compared with other 3D TDSs, for example, β-cristobalite BiO2 (ref. 3) and Na3Bi (refs 4, 5), Cd3As2 is stable and has much higher Fermi velocities. Furthermore, by in situ doping we have been able to tune its Fermi energy, making it a flexible platform for exploring exotic physical phenomena.
authors.affiliation: 1] Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA [2].
authors.forename: Z K
authors.initials: ZK
authors.lastname: Liu
authors.affiliation: 1] Physics Department, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK [2] State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China [3].
authors.forename: J
authors.initials: J
authors.lastname: Jiang
authors.affiliation: 1] Physics Department, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK [2] Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [3].
authors.forename: B
authors.initials: B
authors.lastname: Zhou
authors.affiliation: 1] Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China [2].
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Wang
authors.affiliation: 1] Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA [2] Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: H M
authors.initials: HM
authors.lastname: Weng
authors.affiliation: Physics Department, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
authors.forename: D
authors.initials: D
authors.lastname: Prabhakaran
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: S-K
authors.initials: SK
authors.lastname: Mo
authors.affiliation: Physics Department, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
authors.forename: H
authors.initials: H
authors.lastname: Peng
authors.affiliation: Diamond Light Source, Didcot OX11 0DE, UK.
authors.forename: P
authors.initials: P
authors.lastname: Dudin
authors.affiliation: Diamond Light Source, Didcot OX11 0DE, UK.
authors.forename: T
authors.initials: T
authors.lastname: Kim
authors.affiliation: Diamond Light Source, Didcot OX11 0DE, UK.
authors.forename: M
authors.initials: M
authors.lastname: Hoesch
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Fang
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: X
authors.initials: X
authors.lastname: Dai
authors.affiliation: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA.
authors.forename: Z X
authors.initials: ZX
authors.lastname: Shen
authors.affiliation: State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: D L
authors.initials: DL
authors.lastname: Feng
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Hussain
authors.affiliation: 1] Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA [2] Physics Department, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK [3] Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [4] Diamond Light Source, Didcot OX11 0DE, UK.
authors.forename: Y L
authors.initials: YL
authors.lastname: Chen