Close to the transition between incommensurate conductor and commensurate insulator, charge transport in a system of one-dimensional interacting spin-1/2 fermions moving in a periodic potential is done by solitons (i.e., the few extra particles or holes) having a charge $Q$ which is a fraction of the elementary charge $e$. We show that $Q$ is directly related to the limiting value at commensuration of the exponent $g_c^{*}$ of the charge-charge correlation function: $g_c^{*}=(Q/e{)}^2$. We give some simple rules for determining both charge and spin correlation exponents and point out their dependence on the parity of the order of the underlying umklapp scattering.

• Received 28 November 1994

DOI:https://doi.org/10.1103/PhysRevLett.74.4891