Thermal Conductivity of Ce Doped Bi-2212 Superconductors

The temperature dependence of the thermal conductivity in Bi₂Sr₂Ca_1-xCe_xCu₂O_y x = 0.1, 0.2, 0.3, 0.4 is presented. With increasing Ce-doping level, the thermal conductivity peak under T_c is suppressed then disappears, while another peak appears at low temperatures for the non-superconducting compounds. The numerical analysis shows that the thermal conductivity peak under T_c can be well described by the normal electron relaxation-time contribution model, and the phonon-induced thermal conductivity peak could be well described within the Debye approximation of the phonon spectrum. The existence and variation of these two thermal conductivity peaks indicate the adjustability between the superconducting and insulating components in the samples with different Ce-doping levels.