Synthesis of semimetal A3Bi (A = Na, K) thin films by molecular beam epitaxy.

Three-dimensional (3D) Dirac cones are predicted to reside in semimetals A 3 Bi (A = Na, K). By using molecular beam epitaxy (MBE) and scanning tunneling microscopy (STM), we have successfully established the growth conditions for Na 3 Bi thin films on Si(1 1 1)-7 × 7, and determined that the lattice of Na 3 Bi is rotated by 30 degree with respect to that of Si(1 1 1)-7 × 7. The Na 3 Bi/Si(1 1 1)-7 × 7 thin film was further used as the substrate for the growth of K 3 Bi. The 3D Dirac-cone-like electronic band structures of Na 3 Bi and K 3 Bi have been clearly revealed by angle resolved photoelectron spectroscopy (ARPES). [ABSTRACT FROM AUTHOR]