Figure 6

Energy difference of the lowest conduction band and the top valence band in the Brillouin zone slices of (a) k_x=0.65π, (b) k_y=0.65π, (c) k_z=0.69π. The top panels show the positions of the corresponding slices within the 1/8 Brillouin zone, [0, π]×[0, π]×[0, π]. Note that the background of Supplementary Figure 8a is a small region in the 2 o’clock direction of c. There are prominent white curves in all these panels, on which the lowest conduction band and the top valence band are nearly degenerate; i.e., these white curves indicate the existence of (quasi) nodal surfaces around the Fermi level.