Evolution of fluctuation conductivity of Y1Ba2Cu3O7-Δ single crystals under the influence of medium doses of electron irradiation and doping with praseodymium
In: Visnyk Charkivsʹkoho nacionalʹnoho universytetu imeni V.N. Karazina: Vestnik Charʹkovskogo nacionalʹnogo universiteta imeni V.N. Karazina = Visnyk of V.N.Karazin Kharkiv National University, Issue 38, p. 7-14
The influence of medium doses (from 1019 cm–2 to 1020 cm–2) of irradiation with fast electrons and changes in the concentration of praseodymium in the interval 0.0 ≤ z ≤ 0.5 on the excess conductivity of optimally oxygen-doped Y1Ba2Cu3O7-δ single crystals was studied. It is shown that electron irradiation and an increase in the degree of doping with praseodymium leads to a significant expansion of the temperature interval of the existence of excess conductivity, thereby narrowing the region of the linear dependence of r(Т) in the ab-plane. It was established that at doses 0 ≤ D ≤ 6.5´1019 cm–2 the value of the value of the transverse coherence length ξс(0) increases with an increase in D approximately 3 times and more than four times as the praseodymium content in the sample increases to z ≈ 0.42. At the same time, in both cases, the 2D-3D crossover point is shifted by temperature. In contrast to the case of irradiation with small doses (D ≤ 1019 cm–2) and doping with praseodymium up to concentrations z ≤ 0.39, irradiation with medium doses and doping with praseodymium at higher concentrations leads to a non-monotonic dependence of the transverse coherence length xс(0) with characteristic maxima at D ~ (7-8)´1019 cm–2 and z ≈ 0.42, which may be related to the general suppression of superconducting characteristics.