Microwave response of confined soliton pairs (bipolarons) in (N-methylphenazinium${)}_{\mathrm{x}}$ - (phenazine${)}_{1\mathrm{-}\mathrm{x}}$ (tetracyanoquinodimethanide)

The temperature-dependent dielectric response and conductivity at ≃${10}^{10}$ Hz is reported for the title compound, (NMP${)}_{\mathrm{x}}$(Phen${)}_{1\mathrm{-}\mathrm{x}}$(TCNQ), in the regime 0.50≤x≤0.59, spanning commensurate, bipolaron, and incommensurate regimes. The large and strongly temperature-dependent dieelectric constant and σ${(10\mathrm{}}^{10}$ Hz) are accounted for by a model based on the dynamics of pinned charge-density waves and the presence of relatively mobile charged bipolarons (confined soliton pairs) in the commensurate phase.