  Strong coupling of charge, spin, and lattice in solids brings about emergent
elementary excitations with their intertwining and, in one dimension, solitons
are known as such. The charge-transferred organic ferroelectric, TTF-CA, has
been argued to host charge solitons; however, the existence of the charge
solitons remains unverified. Here, we demonstrate that the charge-transport gap
in the ionic Mott-Peierls insulating phase of TTF-CA is an order of magnitude
smaller than expected from quasiparticle excitations, however, being entirely
consistent with the charge soliton excitations. We further suggest that charge
and spin solitons move with similar diffusion coefficients in accordance with
their coexistence. These results provide a basis for the thermal excitations of
the emergent solitons.
