Dual-Mode Polarization Reversal via Coupled Sliding and Strain in 2D Heterobilayers

Sliding ferroelectricity holds great promise for enabling low-power, high-density nanoscale devices, yet most studies have focused on two-dimensional (2D) homobilayer systems. Using first-principles calculations, we construct MX/NY (M, N = Al, Ga, Si; X, Y = C, N) heterobilayer structures and show that both interlayer sliding and biaxial compressive strain could trigger polarization reversal in all these configurations, suggesting a consistent trend across the six studied III–IV graphene-like heterobilayers within the present periodic first-principles framework. Moreover, the polarization magnitudes surpass those of well-known 2D homobilayer sliding ferroelectrics. Further analysis shows that the stacking-pattern modulation induced by sliding and the local out-of-plane atomic distortion induced by strain within the periodic heterobilayer model are identified as key factors associated with polarization reversal. These results provide a first-principles design perspective for sliding- and strain-responsive ferroelectricity in asymmetric 2D heterobilayers, particularly for supported or mechanically constrained device configurations.