Possible Mechanism of Superconductivity in Ce-Based Heavy Fermion Compounds : Analysis Based on the Third-Order Perturbation Theory

概要

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Heavy fermion compounds CeCu_2X_2 (X=Si, Ge) exhibit a curious enhancement of the super-conducting transition temperature T_c under high pressures. It is not clear whether the superconductivity in these compounds can be explained by the spin-fluctuation mediated one, which is a likely mechanism of heavy fermion superconductors. In order to clarify the mechanism of the superconductivity and the origin of the enhancement, we investigate a 3D periodic Anderson model with its complicated band structure near the Fermi level within the third-order perturbation theory. T_c is estimated on the basis of the Eliashberg equation. It is shown that the irreducible vertex up to the third-order leads to the d_<x^2-y^<2->> wave at the reasonable transition temperature. T_c is sensitive to the f-electron band structure, and the strong 3-dimensionality drastically lowers T_c. Then, it is suggested that the curious behavior of T_c will be explained within the same framework.
社団法人日本物理学会の論文
2002-04-15