Spatially Tunable Interfacial Ferroelectricity in Low-Symmetric WTe₂

Interfacial ferroelectricity, recently discovered in van der Waals (vdW) materials, exhibits switchable dipoles at the interface. Most experiments are realized by stacking high-symmetry two-dimensional (2D) lattices in specific stacking configurations. A prototype based on a synthetic and low-symmetry 2D lattice is robust for switchable dipoles with broken symmetry at the interface. Here, we show that interfacial ferroelectricity can be spatially tunable by controlling the odd-even layer number in the synthetic low-symmetry lattice of 1T'-WTe₂. A high ferroelectric transition temperature (T_C) of >550 K is confirmed. The density functional theory (DFT) calculations indicate that interlayer sliding along the b-axis enables polarization switching of the interfacial dipoles. This study moves a significant step toward spatially tunable interfacial ferroelectricity.