Thermodynamic Properties of the Superconducting State in the K3C60 Fulleride

R. Szczęśniaka and A. Barasiński b a Institute of Physics, Częstochowa University of Technology, al. Armii Krajowej 19, 42-200 Częstochowa, Poland b Institute of Physics, University of Zielona Góra, Prof. Szafrana 4a, 65-516 Zielona Góra, Poland

Received: May 14, 2009; In final form: November 10, 2009

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In the framework of the Eliashberg formalism, we have calculated the thermodynamic properties of the superconducting state in K3C60 (the critical temperature TC = 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 R1 ≡ 2Δp(0)/kBTC and R2 ≡ ΔC(TC)/CN (TC) are bigger than in the BCS model; R1 = 4.01 and R2 = 1.58. (iii) The electron effective mass m*e reaches the highest value for T = TC; [m*e]max = 2.86 me, where me is the bare electron mass. Additionally, we have given the analytical expressions for TC, Δ(T), R1 and R2.

DOI: 10.12693/APhysPolA.116.1053 PACS numbers: 74.20.Fg, 74.70.Wz