Far-infrared hopping conductivity in the CuO chains of a single-domain YBa2Cu3O7- delta crystal.

We report on the observation of far-infrared hopping conductivity in the CuO chains of a single-domain YBa 2 Cu 3 O 7-δ crystal. Our results suggest that at low temperatures the mean free path of carriers in the chains is mainly determined by scattering at oxygen vacancies, while at higher temperatures scattering at phonons occurs additionally