Gate-Tunable Interlayer\nAntiferroelectricity in 2H\nα‑In<sub>2</sub>Se<sub>3</sub>

Recent discovery on van der Waals (vdW) ferroelectrics\nhas inspired\nextensive explorations of two-dimensional emerging heterostructures\nand devices with exotic functionalities. Their innate layer degree\nof freedom allows the realization of an interfacial antiferroelectric\nstate, which is a challenge in bulk perovskite ferroelectrics. Here,\nwe report the observation of gate-tunable interlayer antiferroelectricity\nin 2H-stacked α-In<sub>2</sub>Se<sub>3</sub> with direct electric\ntransport evidence consolidated by nonlinear optical spectroscopy.\nWhen the in-plane polar alignment is electrically switched between\nlayers, a characteristic double hysteresis <i>I–V</i> loop for antiferroelectrics is observed. We observe that the critical\nelectric field of driving interlayer antiferroelectric–ferroelectric\ntransition is gate-voltage dependent with a lowest value realized\nat 7.5 × 10<sup>3</sup> V cm<sup>–1</sup>. The gate-voltage\nmodulation of interlayer antiferroelectricity results from the interplay\nbetween dipole-locked and semiconductor properties of α-In<sub>2</sub>Se<sub>3</sub>. Our findings shed light on the rich ferroelectricity\nin vdW ferroelectrics and suggest a route for the development of antiferroelectric\nelectronics.