Possibility of solitons with charge±e2in highly correlated 1:2 salts of tetracyanoquinodimethane (TCNQ)

Solitons with fractional charge $\frac{\pm e}{2}$ might be experimentally realized in the highly correlated 1:2 salts of tetracyanoquinodimethane (TCNQ) if the quarter-filled TCNQ chains of these compounds correspond to linear Hubbard chains dominated by the on-site Coulomb repulsion. The low-temperature current-carrying excitations of the TCNQ chains would consist of thermally activated pairs of such fractionally charged solitons. The addition of a single electron to a TCNQ chain would lead to the formation of two identical solitons with half-integer charge.