Theory of Superconductivity in CeMIn_5 (M=Co, Rh, Ir) on the Basis of the Three Dimensional Periodic Anderson Model(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

概要

論文の詳細を見る
CeMIn_5 (M=Co, Rh, Ir) are heavy fermion compounds with a HoCoGa_5-type structure. CeCoIn_5 and CeIrIn_5 become superconducting at ambient pressure with T_c=2.3 and 0.4K, respectively. On the other hand, CeRhIn_5 is an antiferromagnet at ambient pressure, and becomes superconducting under pressures greater than 1.6GPa. Nuclear-quadrupole-resonance (NQR), thermal conductivity, specific heat, and electrical resistivity measurements indicate that the superconductivity in CeMIn_5 has line nodes. However, the pairing symmetry between d_<x^2-y^2> and d_<xy> is controversial based on the angle-dependent measurements of thermal conductivity and specific heat under the magnetic field, respectively. Therefore, we investigate the gap structure of CeMIn_5 by a detailed calculation. In order to reproduce the band structure characteristics of CeMIn_5, we introduce a three-dimensional (3D) periodic Anderson model (PAM) and solve the Eliashberg equations. Thus, we identify the gap structure of CeMIn_5 as the d_<x^2-y^2> symmetry. In addition, we discuss the pressure dependence of T_c and show that two opposing factors determine T_c. One factor is the momentum dependence of quasi-particle interaction and the other factor is the wave-function renormalization factor.
社団法人日本物理学会の論文
2006-02-15