Integrated ferroelectricity and spin–orbit proximity in R-stacked bilayer WSe2/graphene heterostructures

Abstract

Van der Waals heterostructures combining graphene with transition metal dichalcogenides (TMDs) provide a versatile platform for optoelectronic and spintronic devices [Georgiou et al., Nat. Nanotechnol. 8, 100 (2013); Britnell et al., Science 340, 1311 (2013); Roy et al., Nat. Nanotechnol. 8, 826 (2013); Novoselov et al., Science 353, aac9439 (2016); and Safeer et al., Nano Lett. 19, 1074 (2019)]. However, the absence of intrinsic ferroelectricity in most TMDs has limited their application in nonvolatile memory and neuromorphic electronics. Here, we show that R-stacked bilayer WSe2 can serve as a ferroelectric dielectric directly coupled with mono- or bilayer graphene, realizing ferroelectric field-effect transistors with nonvolatile, polarization-controlled modulation of carrier density. The devices exhibit endurance exceeding 108 cycles and retention longer than 8000 s, demonstrating robust and fatigue-free ferroelectric switching. Interfacial charge transfer between WSe2 and graphene is found to play a crucial role in determining the hysteresis width. Moreover, Shubnikov–de Haas oscillations reveal clear signatures of band splitting arising from interfacial spin–orbit interactions. Our results establish a synthetic platform that combines ferroelectricity with spin–orbit proximity, opening opportunities for multifunctional devices based on two-dimensional heterostructures.