Towards Sliding Ferroelectricity in Two-Dimensional van der Waals Materials
Sliding ferroelectricity arises from lateral interlayer shifts in stacked two-dimensional van der Waals materials, where relative sliding of one layer over another breaks inversion symmetry and generates switchable polarization. This novel mechanism enables intrinsically nonpolar crystals to exhibit ferroelectric behavior via specific stacking arrangements, expanding the pool of potential ferroelectrics. Distinctive features include ultralow switching barriers, exceptional endurance over millions to trillions of cycles, and ultrafast polarization reversal on sub-nanosecond timescales, surpassing conventional ferroelectrics. This review begins with theoretical models of sliding ferroelectricity, followed by experimental verification and characterization techniques. It then discusses recent advances in polarization-switching kinetics, domain wall dynamics, topological polar structures, multiple polarization states, optical probing, and active modulation strategies. Finally, challenges and future prospects for two-dimensional sliding ferroelectric materials are addressed.