Electrical and thermal properties of bulk superconductors Eu_0.95Pr_0.05Ba₂(Cu_1−xM_x)₃O_7−δ (M = Fe, Ni, Zn and Mn)

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• 作者：Tirthankar Chakraborty ; Bhasker Gahtori ; Ajay Soni ; G.S. Okram ; S.K. Agarwal ; Y.-S. Chen ; Y.-K. Kuo ; Geetha ; Ashok Rao ; Ch ; an Kumar Sarkar
• 关键词：A. High T_C superconductors ; D. Critical field ; C. Transport properties ; D. Specific heat
• 刊名：Physica C
• 出版年：2010
• 出版时间：1 February 2010
• 年：2010
• 卷：470
• 期：3
• 页码：244-249
• 全文大小：1203 K

文摘

Measurements of transition temperature, magneto-resistance, thermal conductivity, thermo-electric power and specific heat have been carried out on co-doped samples of Eu_0.95Pr_0.05Ba₂(Cu_1−xM_x)₃O_7−δ (M = Fe, Ni, Zn and Mn) compounds. It is found that all samples exhibit metallic behavior, except the co-doped sample of Fe that shows semiconducting behavior. It is seen that the upper-critical field H_c2 decreases with Pr-doping. However, an increase in H_c2 for dopants like Fe and Mn is observed. Thermal conductivity for the pristine sample of EuBa₂Cu₃O_7−δ (Eu-123) exhibits a pronounced hump below the superconducting transition temperature T_C. However, the peak height of the hump decreases with Pr-doping and such a feature is further suppressed in the co-doped samples. The negative sign of the measured thermo-electric power of Eu-123 indicates that the dominant carrier in this sample is electron-like, whereas it turns to hole-like for all of the doped samples. A jump in specific heat C_P is detected in the pure sample of Eu-123 at T_C, while only a change in slope in C_P is seen around the transition temperature in the Pr-doped sample.