超伝導体の熱伝導に関する研究 : 第3報, 高温酸化物超伝導体の熱伝導率測定および熱伝導率の構造的温度依存性の検討

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We have measured the thermal conductivities and electrical resistivities of Y_1Ba_2Cu_30_7-_y,Er_1Ba_2Cu_30_7-_y and Bi_1Sr_1Ca_1Cu_20_y using the steady-state comparative method and conventional four-probe method. Below the transition temperature, T_c, the thermal conductivities had strikingly large values and peaks. By applying the Wiedemann-Franz law, λR/T=L_0, with the electrical resistivity data at T_c, the phonon-thermal conductivities were found to predominate in those superconductors. The normalizations of the measured thermal conductivities of those superconductors with respect to λ_c, critical thermal conductivity, show that the temperature dependencies of thermal conductivity are similar. Most of the normalized thermal conductivities agree with our theory, λ_s=2ξ^2・λ_n/(1+ξ^4), in which the value n of the phonon thermal conductivity, λ_n=ξ^n, in the normal conducting state is between -1 and -1.5 below T_c.
一般社団法人日本機械学会の論文
1990-09-25