Polaron transport in quasi-1d organic conductors and in some narrow band systems

A detailed review of large and small polaron transport theory in quasi-1d organic conductors and conducting polymers, and in some narrow band systems including superlattices, superionic conductors and superconductors with heavy fermions is presented. The strong-coupling large polaron mobility is evaluated in 1d and 3d crystals taking account of optical phonon dispersion. The current-voltage characteristics (CVC) for a a 1d acoustic polaron with saturation of the drift velocity V₀( E) in strong fields E→∞ near the sound velocity S is found. This effect has been recently observed by Donovan and Wilson in polydiacetylene PDA TS [8]. The small polaron (SP) spectrum in narrow band conductors is investigated and its strong anisotropy in quasi-1d organic conductors is proved. The CVC for SP is calculated and the characteristic maximum with the negative differential conductivity is found. An exact theory of the Gunn effect in these 1d systems is developed and the explicit analytic expressions for a domain structure are obtained. The domain stability is studied and the possibility of their experimental observing is discussed.