The effect of high-temperature annealing on the temperature dependence of the pseudogap of YBa2Cu3O7–δ single crystals irradiated with high-energy electrons

Abstract

The effect of high-temperature annealing on the basal-plane conductivity of HTSC YBa2Cu3O7–δ single crystals irradiated with high-energy electrons is investigated. It is found that the excess conductivity Δσ(Т) of YBa2Cu3O7–δ single crystals in a broad temperature range Tf<T<T∗ is described by an exponential temperature dependence. Moreover, the description of excess conductivity using the Δσ∼exp(Δab∗/T) relation can be interpreted in terms of the mean-field theory, where T∗ is presented as the average field temperature of the transition to the pseudogap (PG) state, and the temperature dependence of that pseudogap is adequately described in terms of the BCS-BEC crossover theory. The high-temperature annealing results in an unexpected phenomenon: the absolute value of the pseudogap is increased, and the excess conductivity is generally decreased with respect to the initial unirradiated sample.