Low Temperature Physics: 42, 930 (2016); https://doi.org/10.1063/1.4967237
Fizika Nizkikh Temperatur: Volume 42, Number 10 (October 2016), p. 1184-1191    ( to contents , go back )

Investigation of the pseudogap state in Bi2Sr2CaCu2Ox and Bi2Sr2ZnCu2Oy HTSC materials

V.M. Aliev, A.N. Mamedova, S.S. Raqimov, R.I. Selim-zade, and B.A.Tairov

Institute of Physics of Azerbaijan National Academy of Sciences, Baku Az-1143, Azerbaijan
E-mail: v_aliev@bk.ru
pos Анотація:

Received February 1, 2016

Abstract

The influence of substitution of Calcium by Zinc on the transport properties of BiSrCaCuO-2221 system was studied. It was shown that the critical temperatures Tc for Bi2Sr2CaCu2Ox (B1) and Bi2Sr2ZnCu2Oy (B1) are very close (81 K and 81.72 K). However the resistivity ρ of Bi2Sr2ZnCu2Oy sample increases appreciably and the ratio ρВ2В1 10 at 100 K. In the framework of the local pair model we analyzed the origin of excess conductivity in Bi2Sr2CaCu2Ox and Bi2Sr2ZnCu2Oy taking into account Aslamazov-Larkin theory in the vicinity of Tc. We found the temperature T0 for transition from 2D fluctuation area to 3D region (the temperature of 2D-3D crossover). The coherence length of fluctuating Cooper pairs along the c-axis ξс(0) was calculated. Substitution of Ca by Zn results in decrease of ξс(0) by factor of 1.5 (4.8 A and 3.3 A respectively) and narrowing of pseudogap region as well as superconducting fluctuation area near Tc. The temperature dependence of pseudogap Δ*(Т) and Δ*(Тс) were determined. Increase of ρ and its specific temperature dependence together with significant decrease of T* indicates destruction of local pairs at high temperatures i.e. suppression of pseudogap as a result of Zn doping.

PACS: 74.20.Mn Nonconventional mechanisms
PACS: 74.72.–h Cuprate superconductors
PACS: 74.25. ± q Properties of superconductors
PACS: 74.25.Jb Electronic structure (photoemis-sion, etc.).

Key words: superconductivity, pseudogap, excess conductivity, Bi2Sr2ZnCu2Ox, coherent length, crossover temperature.

Published online: August 25, 2016

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