title: Discovery of a three-dimensional topological Dirac semimetal, Na3Bi.
abstract: Three-dimensional (3D) topological Dirac semimetals (TDSs) represent an unusual state of quantum matter that can be viewed as "3D graphene." In contrast to 2D Dirac fermions in graphene or on the surface of 3D topological insulators, TDSs possess 3D Dirac fermions in the bulk. By investigating the electronic structure of Na3Bi with angle-resolved photoemission spectroscopy, we detected 3D Dirac fermions with linear dispersions along all momentum directions. Furthermore, we demonstrated the robustness of 3D Dirac fermions in Na3Bi against in situ surface doping. Our results establish Na3Bi as a model system for 3D TDSs, which can serve as an ideal platform for the systematic study of quantum phase transitions between rich topological quantum states.
authors.affiliation: Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
authors.forename: Z K
authors.initials: ZK
authors.lastname: Liu
authors.forename: B
authors.initials: B
authors.lastname: Zhou
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Wang
authors.forename: H M
authors.initials: HM
authors.lastname: Weng
authors.forename: D
authors.initials: D
authors.lastname: Prabhakaran
authors.forename: S-K
authors.initials: SK
authors.lastname: Mo
authors.forename: Z X
authors.initials: ZX
authors.lastname: Shen
authors.forename: Z
authors.initials: Z
authors.lastname: Fang
authors.forename: X
authors.initials: X
authors.lastname: Dai
authors.forename: Z
authors.initials: Z
authors.lastname: Hussain
authors.forename: Y L
authors.initials: YL
authors.lastname: Chen