Hopping Motion of Small Polarons Versus Temperature and Dimensionality

The effects of dimensionality on the small polaron motion have been studied through a molecular crystal model in which the intermolecular forces are described by a first neighbors pair potential. The crossover temperature between band-like and hopping motion is sensibly reduced in low-dimensional systems due to the enhanced importance of the off-diagonal scattering processes. The dispersion in the phonon spectrum is essential for the validity of the model. The results may be of interest in order to understand the anomalous c-axis electrical transport in high-Tc superconductors