  Two-dimensional (2D) materials occupy noteworthy place in nanophotonics
providing for subwavelength light confinement and optical phenomena dissimilar
to those of their bulk counterparts. In the mid-infrared, graphene-based
heterostructures and van der Waals crystals of hexagonal boron nitride (hBN)
overwhelmingly concentrate the attention by exhibiting real-space nano-optics
from plasmons, phonon-polaritons and hybrid plasmon phonon-polaritons
quasiparticles. Here we present the mid-infrared nanophotonics of talc, a
natural atomically flat layered material, and graphene-talc (G-talc)
heterostructures using broadband synchrotron infrared nano-spectroscopy. We
achieve wavelength tuning of the talc resonances, assigned to in- and
out-of-plane vibrations by changing the thickness of the crystals, which serves
as its infrared fingerprints. Moreover, we encounter coupling of the graphene
plasmons polaritons with surface optical phonons of talc. As in the case of the
G-hBN heterostructures, this coupling configures hybrid surface plasmon
phonon-polariton modes causing 30 % increase in intensity for the out-of-plane
mode, blue-shift for the in-plane mode and we have succeeded in altering the
amplitude of such hybridization by varying the gate voltage. Therefore, our
results promote talc and G-talc heterostructures as appealing materials for
nanophotonics, like hBN and G-hBN, with potential applications for controllably
manipulating infrared electromagnetic radiation at the subdiffraction scale.
