The calcium effect on the thermopower, critical temperature and charge-carrier system parameters in the Y0.75-xCaxPr0.25Ba2Cu3Oy HTSC-system




high-temperature superconductors, calcium doping, critical temperature, thermopower, narrow-band model, normal-state energy spectrum, Fermi level


Superconducting properties and thermopower temperature dependences for two series of ceramic samples with Y0.75-xCaxPr0.25Ba2Cu3Oy (x = 0–0.25) compositions are experimentally investigated. Thermopower temperature dependences are analysed using the phenomenological narrow-band model. The normal state energy spectrum and the charge-carrier system parameters including the Fermi level position are determined and the doping influence on their value is discussed. It is shown that the Fermi level position in Y0.75-xCaxPr0.25Ba2Cu3Oy samples is determined by its pinning inside a local peak in the density-of-states function formed due to increasing calcium content. The influence of the observed normal-state energy spectrum modification on the critical temperature in the studied system is discussed.


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Condensed Matter Physics