Large out-of-plane piezoelectric response of ferromagnetic monolayer MoXF (X<b>=</b>S, Se): First principles predictions

With both piezoelectric and ferromagnetic states, two-dimensional (2D) materials have garnered significant interest due to their immense potential in the field of spintronic devices. In this paper, the stability, electronic structure, piezoelectric properties, and magnetic characteristics of 2D piezoelectric ferromagnetic semiconductor MoXF (X = S, Se) monolayers were systematically investigated through first-principles calculations and Monte Carlo simulations. It is found that both MoSF and MoSeF are stable intrinsic ferromagnetic semiconductors and exhibit excellent out-of-plane piezoelectric coefficients (d31) of 1.05 and 1.40 pm/V, respectively, which surpass most 2D materials. They also possess out-of-plane magnetic anisotropy energy and high Curie temperatures (Tc, 227 and 210 K, respectively). In addition, biaxial strain has a significant effect on the piezoelectric properties and magnetic properties of MoSeF monolayers, which can enhance the application potential of the material. The findings suggest that MoXF monolayers hold tremendous potential for multifunctional semiconductor spintronic applications.