Supplement Number 1

The calculation details are shown in the supplementary material, including the system energy of the eight magnetic configurations of the TMMn2I6 (TM=V, Cr) monolayer, the structural diagram, and energy of the different magnetic moment orientations when SOC effects are taken into account, the schematic diagram of the nearest neighbor exchange J, the schematic diagram of the calculated electronic structure considering SOC in the ferromagnetic state, and the schematic diagram of the MAE orbital contribution of the original MnI3 monolayer.