Thermodynamic Properties in Triangular-Lattice Superconductors.

The study of superconductivity arising from doping a Mott insulator has become a central issue in the area of superconductivity. Within the framework of the kinetic-energy-driven superconducting (SC) mechanism, we discuss the thermodynamic properties in the triangular-lattice cobaltate superconductors. It is shown that a sharp peak in the specific heat appears at the SC transition temperature $$T_\mathrm{c}$$ , and then the specific heat varies exponentially as a function of temperature for temperatures $$T<T_\mathrm{c}$$ due to the absence of d-wave gap nodes at the charge-carrier Fermi surface. In particular, the upper critical field follows qualitatively the Bardeen-Cooper-Schrieffer-type temperature dependence, and has the same dome-shaped doping dependence as $$T_\mathrm{c}$$ . [ABSTRACT FROM AUTHOR]