YBa_(2-x)Pr_xCu_3O_(7-δ)体系中的Pr替代效应

EFFECTS OF Pr SUBSTITUTION IN YBa_(2-x)Pr_xCu_3O_(7-δ) SYSTEM

报道了YBa_(2-x)Pr_xCu_3O_(7-δ)(0≤x≤0.15)体系的超导电性和正常态输运性质的测量。实验结果表明随着Pr在Ba晶位替代量的增加,超导转变临界温度T_c和由Hall系数推算的荷电载流子浓度P_H均单调下降。通过与Y_(2-x)Pr_xBa_2Cu_3O_(7-δ)和Nd_(1+x)Ba_(2-x)Cu_3O_(7-δ)体系的比较研究,作者发现上述三个体系的T_c变化均与载流子浓度的变化相关联。作者进而提出,在YBa_(2-x)Pr_xCu_3O_(7-δ)体系中Pr的空穴填充效应导致可迁移空穴浓度下降,从而压制T_c;而在Y_(2-x)Pr_xBa_2Cu_3O_(7-δ)体系中载流子浓度的下降则是主要来源于Pr替代对空穴的局域作用,T_c同样被压制。Pr的拆对效应不明显。

The measurements of superconductivity and normal state transport properties of YBa2-xPrxCu3O7-δ system is reported. The experimental results show that both the superconducting transition temperature (Tc) and the charge carrier concentration (PH) deduced from the Hall coefficient of the samples drop monotonously with the increase of Pr content. Comparing with the data of Y1-xPrxBa2Cu3O7-δ and Nd1+x-Ba2-xCu3O7-δ systems, it is found that the variations of T_c in all the three systems are connected with the changes of the carrier density. We suggest that the suppres-sion of T_c in YBa2-xPrxCu3O7-δ system is caused by the decrease of the mobile hole density induced by Pr's hole-filling effects, while the depression of the mobile hole density, therefore Tc in Y1-xPrxBa2Cu3O7-δ system is due to the Pr's hole-localization effects. The pair-breaking effect of Pr is insignificant in these systems.