Fig. 1: Geometric structures of known monolayer 2D materials and new MA2Z4 monolayer materials.

a Top and side views of representative monolayers for n ≤ 7, all belonging to the SMR materials17. b Schematic illustration of the intercalation method that uses the structures of a MoS2-like monolayer (2H- and 1T phases) and those of an InSe-like monolayer (α and β phases) to construct the structures of a MA2Z4 monolayer.