Extended Data Fig. 2: Electron diffraction analysis of a mechanically exfoliated α-Bi4Br4.

flake.a, Scanning electron microscopy image of rectangular-shaped α-Bi4Br4 thin flakes on a Si substrate. The crystallographic plane and the axes are indicated for the largest flake used for the diffraction analysis. b, Transmission electron microscopy image displaying the cross-section of the thin flake, which is perpendicular to the long axis of the flake. Inset: corresponding electron diffraction pattern from the [010] zone axis.