Low Ferroelectric Switching Barriers and Stacking-Insensitive Electronic Structures in CrX ₂ (X = S, Se, Te) Bilayers Enabled by Weak Interlayer Coupling

Two-dimensional (2D) ferroelectrics are highly promising for next-generation nonvolatile memory and low-power nanoelectronic devices, owing to their atomic-scale thickness and tunable polarization. Among these, sliding ferroelectricity in artificially stacked nonpolar 2D materials offers a versatile route to achieve switchable polarization across a broad class of layered systems. Here, using first-principles calculations combined with a semiempirical van der Waals (vdW) dispersion correction, we systematically investigated the electronic structure and sliding ferroelectricity of CrX2 (X = S, Se, Te) bilayers. We uncover a cooperative control mechanism, where the increasing atomic radius and decreasing electronegativity of the chalcogen element (X) jointly modulate both the out-of-plane vdW interactions and the in-plane Cr-3d/X-pz orbital hybridization. This interplay leads to a dramatic reduction in the polarization switching barrier from 5.47 to 0.18 meV per unit cell as well as a concurrent decrease in out-of-plane polarization from 0.61 pC/m to 0.02 pC/m as X changes from S to Te, primarily driven by weakened interlayer coupling. Moreover, the electronic structures and elastic constants of CrX2 bilayers remain largely insensitive to stacking configuration, further corroborating the weak interlayer interactions. In the most stable BA stacking, the band gap exhibits a clear elemental dependence, systematically decreasing from 1.44 eV (CrS2) to 1.05 eV (CrTe2). These findings highlight a critical synergistic effect between elemental composition and interlayer coupling in modulating 2D ferroelectricity, offering fundamental design principles for future high-density, low-power memory and logic devices.