Thermodynamic Properties of the Superconducting State in the $K_{3}C_{60}$ Fulleride

In the framework of the Eliashberg formalism, we have calculated the thermodynamic properties of the superconducting state in $K_{3}C_{60}$ (the critical temperature $T_C$ = 19.50 K). We have obtained the following results: (i) The critical value of the Coulomb pseudopotential is equal to 0.387. (ii) The values of the ratios $R_1$ ≡ 2Δp(0)/$k_{B}T_C$ and $R_2$ ≡ $ΔC(T_C)//C^{N}(T_C)$ are bigger than in the BCS model; $R_1$ = 4.01 and $R_2$ = 1.58. (iii) The electron effective mass $m_{e}^\ast$ reaches the highest value for $T = T_C$; [$m_{e}^\ast]_\text{max}$ = 2.86 $m_{e}$, where $m_{e}$ is the bare electron mass. Additionally, we have given the analytical expressions for $T_C$, Δ(T), $R_1$ and $R_2$.