Discovery of a Three-Dimensional Topological Dirac Semimetal, Na3Bi

• Published in: Science (American Association for the Advancement of Science) Vol. 343; no. 6173; pp. 864 - 867
• Main Authors: Liu, Z. K., Zhou, B., Zhang, Y., Wang, Z. J., Weng, H. M., Prabhakaran, D., Mo, S.-K., Shen, Z. X., Fang, Z., Dai, X., Hussain, Z., Chen, Y. L.
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 21.02.2014; The American Association for the Advancement of Science
• Subjects: 3-D graphics; Binding energy; Doping; Electronic structure; Emissions; Fermions; Graphene; Materials science; Mathematical surfaces; Metalloids; Photoelectric emission; Spectroscopy; Topological manifolds; Topology
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1245085

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.