Fizika Nizkikh Temperatur: Volume 45, Number 11 (November 2019), p. 1434-1438 ( to contents , go back )
The influence of high-temperature annealing on the temperature dependence of the pseudogap of YBa2Cu3O7–δ single crystals irradiated with high-energy electrons
G.Ya. Khadzhai, R.V. Vovk, and Z.F. Nazyrov
V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv 61022, Ukraine
Received July 15, 2019, revised September 9, 2019, published online September 27, 2019
The influence of high-temperature annealing on the conductivity in the basal plane of HTSC YBa2Cu3O7–δ single crystals after their irradiation with high-energy electrons is investigated. It was found that the excess conductivity Δσ(Т) of YBa2Cu3O7–δ single crystals in a wide temperature range Tf < Т < T* is subject to an exponential temperature dependence. Moreover, the description of excess conductivity using the relation σΔ ~ exp(Δ*ab /T ) 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 state, and the temperature dependence of the pseudogap is satisfactorily described in the framework crossover theory BCS–BEC. High-temperature annealing leads to an unusual effect of increasing the absolute value of the pseudogap value and a general decrease in the excess conductivity compared to the ini-tial unirradiated sample.
Key words: excess conductivity, electron irradiation, YВaCuO single crystals, crossover, pseudogap state.