First-principles study on the ferroelectricity properties of two-dimensional SnTe films

The ferroelectric properties of low-dimensional nanomaterials have become one of the hot spots in the field of materials science. Two-dimensional (2D) SnTe films are confirmed to possess very strong in-plane ferroelectricity compared to bulk SnTe. However, the existence of surface effect and size effect restricts the application of traditional bulk ferroelectric materials at the nanoscale. Consequently, the substrate effects and single atom adsorption effects should be of great concern to control the 2D ferroelctricity. Here, these two effects on the ferroelectric properties of layered SnTe were investigated by the Vienna Ab initio Simulation Package (VASP) code based on density functional theory (DFT). Our results indicate the suitable substrates can significantly enhance the ferroelectricity of two-dimensional SnTe and the coexistence of the ferromagnetism and ferroelectric (i.e. multiferroics) is observed in some single atom adsorbed SnTe. It is found that, in Pt- and MgO-supported SnTe films, the in-plane polar displacement is significantly enhanced, with adsorbing H and B have nonzero magnetic moments and good stability. According to our study, we find two way to control the properties of 2D SnTe maybe can obtaining the multiferroicity and magnetoelectric coupling.