A simple rule for finding Dirac cones in bilayered perovskites

Chen Xuejiao^{1, 2}, Liu Lei^{1, †}, Shen Dezhen^{1, ‡}

The crystal structures of Cs₃Bi₂Br₉ (a) in its primitive cell, (b) from the side view, and (c) from the top view along its natural hexagonal axis, and the calculated electronic band structures of (d) bilayer and (e) bulk Cs₃Bi₂Br₉, where the insets zoom in their Dirac bands below the Fermi level.