Heat capacity jump at T-c and pressure derivatives of superconducting transition temperature in the Ba1-xNaxFe2As2 (0.1 <= x <= 0.9) series

Article

关键词: IRON;    CHEMISTRY;   

DOI  :  10.1103/PhysRevB.89.014510

来源: SCIE

【 摘 要 】

We present the evolution of the initial (up to similar to 10 kbar) hydrostatic pressure dependencies of T-c and of the ambient pressure, and the jump in the heat capacity associated with the superconducting transition as a function of Na doping in the Ba1-xNaxFe2As2 family of iron-based superconductors. For Na concentrations 0.15 <= x <= 0.9, the jump in specific heat at T-c, Delta C-p|(Tc), follows the Delta C-p proportional to T-3 (the so-called BNC scaling) found for most BaFe2As2-based superconductors. This finding suggests that, unlike the related Ba1-xKxFe2As2 series, there is no significant modification of the superconducting state (e. g., change in superconducting gap symmetry) in the Ba1-xNaxFe2As2 series over the whole studied Na concentration range. Pressure dependencies are nonmonotonic for x = 0.2 and 0.24. For other Na concentrations, T-c decreases under pressure in an almost linear fashion. The anomalous behavior of the x = 0.2 and 0.24 samples under pressure is possibly due to the crossing of the phase boundaries of the narrow antiferromagnetic tetragonal phase, unique for the Ba1-xNaxFe2As2 series, with the application of pressure. The negative sign of the pressure derivatives of T-c across the whole superconducting dome (except for x = 0.2) is a clear indication of the nonequivalence of substitution and pressure for the Ba1-xNaxFe2As2 series.

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