  Inspired by recent advancement of low-power ferroelectic-gated memories and
transistors, we propose a design of ferroelectic-gated nanoplasmonic devices
based on graphene sheets clamped in ferroelectric crystals. We show that the
two-dimensional plasmons in graphene strongly couple with the phonon-polaritons
in ferroelectrics at terahertz frequencies, leading to characteristic modal
wavelength of the order of 100--200 nm at only 3--4 THz. By patterning the
ferroelectrics into different domains, one can produce compact on-chip
plasmonic waveguides, which exhibit negligible crosstalk even at 50 nm
separation distance. Harnessing the memory effect of ferroelectrics, low-power
electro-optical switching can be achieved on these plasmonic waveguides.
