Extended Data Fig. 1: Reproduced SHG and LD responses of NiI₂ (ref. ¹), CrI₃ (ref. ⁷) and FePS₃ (ref. ⁸).

Temperature dependence of SHG intensity a, for one- to four-layer NiI₂ and b, for CrI₃ bilayer. c, LD intensity as a function of temperature for a FePS₃ multilayer, showing a phase transition at 118 K. The data are collected from ref. ^1,7,8.