Ground state and excitations at low temperature in density wave systems

At low temperature, the charge density wave (CDW) is a well developed three dimensional superstructure—“an electric body”—with energy gap Δ. In the ground state of this superstructure two main types of excitations can be developed: single particle excitations due to thermal generation across the gap and collective excitations—amplitude and phase solitons—due to local deformation moving through the crystal as quasi-particles. It will be shown that CDW excitations dominate the physical transport properties at temperatures below half the Peierls transition temperature. Low frequency dielectric measurements at lower temperatures will be interpreted as a transition of the CDW into a glassy-like state.