Ferroelectric-assisted charge-transfer plasmons in graphene/CuInP2S6
- Yinming Shao
- Hae Yeon Lee
- Jin Zhang
- S. L. Moore
- Shizhe Zhou
- Carlton Drew
- Anjaly Rajendran
- Jacob Amontree
- Thomas P. Darlington
- Daniel G. Chica
- Chun-Ying Huang
- Seng Huat Lee
- Saugata Sarker
- Kenji Watanabe
- Takashi Taniguchi
- Venkatraman Gopalan
- Zhiqiang Mao
- X.-Y. Zhu
- Xavier Roy
- P. James Schuck
- Angel Rubio
- James C. Hone
- D. N. Basov
2026-08-17
Two-dimensional materials and their van der Waals heterostructures provide a versatile platform for novel optoelectronic functionalities. Interfacial charge transfer in such stacks enables high-quality graphene plasmons, but the charge-doping is fixed by work-function differences between constituent layers. Ferroelectric substrates have been explored for non-volatile, switchable doping, yet oxide ferroelectrics yield only modest doping due to imperfect interfaces. Here, we report efficient charge transfer between graphene and the van der Waals ferroelectric CuInP 2 S 6 , where the atomically-sharp interface yields unexpectedly large doping and high-quality plasmons, despite orders-of-magnitude smaller polarizations compared to oxide ferroelectrics. Infrared nano-imaging directly visualizes graphene plasmons whose doping depends on the adjacent ferroelectric layer. Combined nano-infrared and piezoresponse force microscopies reveal that graphene doping and CuInP 2 S 6 polarization increase with thickness and saturate in tandem, linking charge-transfer doping and out-of-plane ferroelectricity. Our results establish ferroelectric-assisted charge-transfer plasmons in graphene/CuInP 2 S 6 as a promising route to probe and control nanoscale ferroelectric textures.