Soloviov A. Fluctuation conductivity and pseudogap in high temperature superconductors

Object is high-temperature supercoductor films with different oxygen concentration including films with artificially produced defects and systems with Pr. Method of recearch is investigation of the excess conductivity taking transition from local pairs to BCS regime into account. The fluctuation conductivity of well structured but low dopped YBCO films, YBCO films with Тс = 80 K as well as of YBCO films with artificially produced defects, YPrBCO films and YBCO-YPrBCO superlattices was studied. The phase relaxation time for all these samples was measured. The methodical approach to the pseudogap analysis in HTSC has been developed. Based on the experimental data analysis an equation for temperature dependence of pseudogap was obtained. For the first time temperature dependencies of pseudogap of YBCO films with different oxygen concentration as well as of YPrBCO films have been studied in detales. All dependencies show evident pseudogap maximum.