Gate-Tunable Interlayer Antiferroelectricity in 2H α-In₂Se₃

Recent discovery on van der Waals (vdW) ferroelectrics has inspired extensive explorations of two-dimensional emerging heterostructures and devices with exotic functionalities. Their innate layer degree of freedom allows the realization of an interfacial antiferroelectric state, which is a challenge in bulk perovskite ferroelectrics. Here, we report the observation of gate-tunable interlayer antiferroelectricity in 2H-stacked α-In2Se3 with direct electric transport evidence consolidated by nonlinear optical spectroscopy. When the in-plane polar alignment is electrically switched between layers, a characteristic double hysteresis I–V loop for antiferroelectrics is observed. We observe that the critical electric field of driving interlayer antiferroelectric–ferroelectric transition is gate-voltage dependent with a lowest value realized at 7.5 × 103 V cm–1. The gate-voltage modulation of interlayer antiferroelectricity results from the interplay between dipole-locked and semiconductor properties of α-In2Se3. Our findings shed light on the rich ferroelectricity in vdW ferroelectrics and suggest a route for the development of antiferroelectric electronics.