Excess conductivity and the pseudogap state in Hf-doped YBa2Cu3O7-δ ceramics

The electrical conductivity of hafnium (Hf)-doped YBa2Cu3O7-delta ceramics is investigated. Hf doping has been revealed to lead to an increase of the number of effective scattering centers for the normal charge carriers. In a broad temperature range, the excess conductivity of the investigated samples obeys an exponential temperature dependence, while near T-c it is satisfactorily described by the Aslamazov-Larkin model. Meanwhile, Hf doping has been shown to lead to a notable broadening of the temperature range for the manifestation of the pseudogap anomaly in the ab-plane.