INFLUENCE OF HIGH PRESSURE ON THE TEMPERATURE-DEPENDENCE OF THE PSEUDO-GAP IN OXYGEN DEFICIENT YBa2Cu3O7-δ SINGLE CRYSTALS

Abstract

The influence of high pressure on the conductivity in the ab-plane of the oxygen deficient YBa 2 Cu 3 O 7-δ single crystals is investigated. It is determined that excess conductivity Δσ(T) in the YBa 2 Cu 3 O 7-δ single crystals in a wide temperature interval (Tc < T < T*, where Tc is the critical temperature and T* is the temperature that the PG regime begins) obeys an exponential temperature-dependence. The description of the excess conductivity with [Formula: see text]) can be interpreted in terms of mean field theory. The temperature-dependence of the pseudo-gap is well described in the framework of the Bardeen–Cooper–Schrieffer (BCS) to the Bose–Einstein condensate (BEC) crossover theory. Increasing the applied pressure leads to the effect of narrowing the temperature range of implementation of the PG regime, thus extending the area of linear ρ(T) dependence in the ab-plane.