On the Thermodynamic Critical Field for the K3C60 and Rb3C60 Fullerides

A.P. Durajski and R. Szczęśniak Institute of Physics, Częstochowa University of Technology, al. Armii Krajowej 19, 42-200 Częstochowa, Poland

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In the paper the temperature dependence of the thermodynamic critical field (Hc) for the alkali-metal-doped fullerides K3C60 and Rb3C60 has been considered. The numerical calculations have been conducted in the framework of the Migdal-Eliashberg formalism. It has been shown that the obtained numerical values of Hc agree with the experimental data. Finally, the dimensionless ratio: RH ≡ TcCN (Tc)/H2c(0) has been calculated, where Tc is the critical temperature and CN denotes the specific heat in the normal state. The theoretical analysis has proved that for the considered fullerides the parameter RH is beyond the BCS prediction. In particular: RH = 0.143 for K3C60, and RH = 0.145 for Rb3C60.

DOI: 10.12693/APhysPolA.126.342 PACS numbers: 74.20.Fg, 74.25.Bt, 74.62.Fj