Comparative analysis of the effect of La and Co on the superconductivity and energyband spectrum of YBa2Cu3Oy for different oxygen contents |
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Authors: | V É Gasumyants E V Vladimirskaya M V Elizarova I B Patrina |
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Institution: | (1) St. Petersburg State Technical University, 195251 St. Petersburg, Russia;(2) Institute of Silicate Chemistry, Russian Academy of Sciences, 195155 St. Petersburg, Russia |
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Abstract: | Temperature dependences of the resistivity and Seebeck coefficient of Y(Ba1−x
Lax)2Cu3Oy and YBa2Cu3−x
CoxOy samples (x=0–0.25) have been measured under maximum sample saturation with oxygen, as well as following their anneal in an oxygen-deficient
atmosphere. The T
c (x) dependences for as-prepared samples were found to pass through a maximum at x=0.05, which persists after annealing for Y(Ba1−xLax)2Cu3Oy and disappears for YBa2Cu3−x
CoxOy. A phenomenological model of the band spectrum in normal phase has been used to determine the parameters of the conduction
band and of the carrier system, and to analyze their variation with the dopant type and content, as well as with annealing.
Despite the differences observed in the T
c (x) dependence, the critical temperatures for all the sample series studied were found to correlate with the conduction-band
effective width. The mechanism of the effect of impurities on the band-structure parameters and the reasons for the different
influence of annealing on the properties of Y(Ba1−x
Lax)2Cu3Oy and YBa2Cu3−x
CoxOy are discussed.
Fiz. Tverd. Tela (St. Petersburg) 41, 389–394 (March 1997) |
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