Supplementary Online Material

Structure parameters, Curie temperature, band structure and DOS. Structural parameters in the ZnIn2S4 monolayer (Table S1). The relationship between energy and strain, band structure and DOS of ZnIn2S4 monolayer under a 5% biaxial tensile strain (Fig. S1). ZnIn2S4 monolayer with ferromagnetic (a) and antiferromagnetic (b) orders. (Fig. S2). The effect of vertical downward external electric field on magnetic moment, Curie temperature and energy difference between FM and AFM states (Fig. S3). Band structure and DOS of ZnIn2S4 bilayers under different biaxial strains (Fig. S4). The net spin charge density distribution under a 5% biaxial tensile strain (Fig. S5). The kinetic pathway of polarization reversal in ZnIn2S4 monolayer (Fig. S6). The band structures during polarization reversal process (Fig. S7). The band structure and DOS after the polarization reversal of ZnIn2S4 monolayer (Fig. S8). Layer-resolved DOS of heterostructures (Fig. S9).