Emergent Phenomena in Ferroelectric/van der Waals Heterostructures

The heterointerfaces between ferroelectrics and 2D van der Waals (vdW) materials can be utilized to achieve novel interfacial coupling, nonvolatile field effect control, and nanoscale programmable functionalities. In this talk, I will discuss a range of emergent phenomena in ferroelectric/vdW heterostructures mediated by interfacial charge, lattice, and polar coupling. Ferroelectric copolymer P(VDF-TrFE) has been utilized to induce nonvolatile conduction modulation in mono- to few-layer MoS₂ and ReS₂, with conductivity switching ratio of >1.5x10⁸ achieved. Combining the ferroelectric field effect with nanoscale domain patterning enables local tuning of carrier density in the vdW channel, which can lead to programmable Schottky junction states in MoS₂ [1]. This approach has also been exploited to create directional conducting paths in an insulating ReS₂ channel, which reveals that the conductivity along and perpendicular to the Re-chain can differ by >5.5×10⁴ in monolayer ReS₂ and further points to the emergence of a flat band in 4-layer ReS₂ [2]. We show that the interface-epitaxy between P(VDF-TrFE) and 1T’-ReS₂ leads to the formation of large scale P(VDF-TrFE) thin films composed of highly ordered, close-packed crystalline nanowires with well-defined width (10 and 35 nm) [3]. We also observe an unconventional filtering effect of second harmonic generation signal, which is attributed to the polar alignment between monolayer MoS₂ and the chiral rotation of surface dipoles at the domain walls in ferroelectric oxide PbZr_0.2Ti_0.8O₃ [4]. Our study showcases the rich research opportunities offered by integrating ferroelectrics with 2D materials.