Characterization of the high-pressure superconductivity in the Pnma phase of calcium

R. Szczesniak, D. Szczesniak

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    The thermodynamic parameters of the superconducting state in calcium under the pressure of 161GPa have been calculated within the framework of the Eliashberg approach. It has been shown that the value of the Coulomb pseudopotential is high (μ* C=0.24) and the critical temperature (TC=25K) should be determined from the modified Allen-Dynes formula. In addition, it has been found that the basic dimensionless ratios of the thermodynamic parameters significantly diverge from the BCS predictions, and take the following values: (i) The zero-temperature energy gap to the critical temperature (R1≡ 2Δ(0)/kBTC) is equal to 4.01. (ii) The ratio R2≡ (CS(TC) equals 2.17, where CSand CNdenote the specific heats for the superconducting and normal states, respectively. (iii) The quantity R3≡TCCN(TC)/H2 C(0)=0.158, where HCindicates the thermodynamic critical field. Finally, it has been proven that the electron effective mass is large and takes the maximum of 2.32meat TC.

    Original languageEnglish
    Pages (from-to)2194-2201
    Number of pages8
    JournalPhysica Status Solidi (B) Basic Research
    Issue number11
    Publication statusPublished - Nov 2012



    • Ca Pnma phase
    • High-pressure effects
    • Superconductivity
    • Thermodynamic properties

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Condensed Matter Physics

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