Nonlinear Optical Responses in 2D Multiferroic VOX₂ (X=Cl, Br, I)

Two-dimensional (2D) multiferroic materials have recently emerged as versatile platforms for multifunctional nanoelectronic and optoelectronic applications, owing to the strong coupling among orbital, spin, and lattice degrees of freedom. Among them, the VOX₂ family exhibits both robust ferroelectricity and intrinsic antiferromagnetism within a single layer. In this work, we perform first-principles calculations to investigate their nonlinear optical responses and found that the pronounced in-plane polarization in these systems leads to strong nonlinear responses. Furthermore, distinct magnetic configurations are found to significantly modulate the nonlinear responses, indicating a strong coupling between ferroelectric and magnetic orders. Our results provide deeperunderstanding of nonlinear responses in 2D multiferroics and open new avenues for developing 2D nonlinear optical and spintronic devices.