On the thermodynamic properties of the Rb3C60 superconductor

•Thermodynamic parameters of the superconducting state that induces in Rb3C60 fulleride.•The high value of Coulomb pseudopotential and critical temperature.•The non-BCS value of the ratio 2Δ/kBTC.•The large electron effective mass.

The thermodynamic properties of the superconducting state in Rb3C60 fulleride have been studied in the framework of the Migdal–Eliashberg approach. In the first step, the high physical value of the Coulomb pseudopotential has been predicted (μC★=0.33), which corresponds to the screened Coulomb potential UC=0.61eV. Next, the temperature dependence of the order parameter and the wave function renormalization factor has been calculated. On the basis of the obtained results, the ratio of the energy gap to the critical temperature (RΔ≡2Δ(0)/kBTCRΔ≡2Δ(0)/kBTC), the ratio of the specific heat jump to the normal state specific heat (RC≡ΔC(TC)/CN(TC)RC≡ΔCTC/CNTC), and the parameter connected with the thermodynamic critical field (RH≡TCCNTC/HC2(0)) have been estimated. It has been shown that the above parameters significantly differ from the BCS predictions: RΔ=4.06,RC=2.15RΔ=4.06,RC=2.15, and RH=0.145RH=0.145. Finally, the temperature dependence of the electron effective mass (me★) has been presented; me★ assumes maximum at the critical temperature: 2.27me2.27me, where meme denotes the electron band mass. In the paper, the obtained theoretical results have been also compared with the experimental data.