Molecular beam epitaxial growth of a three-dimensional topological Dirac semimetal Na₃Bi

We report a molecular beam epitaxial growth of Na₃Bi single-crystal thin films on two different substrates—epitaxial bilayer graphene terminated 6H-SiC(0001) and Si(111). Using reflection high-energy electron diffraction, we found that the lattice orientation of the grown Na₃Bi thin film was rotated by 30° respect to the surface lattice orientations of these two substrates. An in-situ angle-resolved photoemission spectroscopy clearly revealed the 3-dimensional Dirac-cone band structure in such thin films. Our approach of growing Na₃Bi thin film provides a potential route for further studying its intriguing electronic properties and for fabricating it into practical devices in future.