高T_c氧化物Bi_(1.4)Pb_(0.6)Sr_2Ca_2Cu_3O_y大块超导体的弱连结和弱钉扎性质  

WEAK LINKS AND WEAK PINNING CHARACTERISTICS OF HIGH T_c Bi_(1.4)Pb_(0.6)Sr_2Ca_2Cu_3O_y BULK SUPERCONDUCTOR

作　　者：曹效文[1] 黄孙利 张伟杰[2] 刘宏宝[2] 毛志强[2] 周玲[2] 毛向雷 张裕恒 

机构地区：[1]中国科学院等离子体物理所,合肥230031 [2]中国科技大学物理系,合肥230026

出　　处：《低温物理学报》1990年第4期299-306,共8页Low Temperature Physical Letters

摘　　要：掺Pb的Bi_(1.4)Pb_(0.6)Sr_2Ca_2Cu_3O_y氧化物是一个以110K 超导相为主的高 T_c 超导体,其零电阻 T_c 为107.1K. dc Meissner 效应表明,110K 相占样品体积的8.2%,85K 相占1.6%.不同磁场下的排磁通(Meissher)效应,超导体所占体积上限和下限的比较,不同磁场和测量电流的 R(T)超导转变,表明了样品中存在着丰富的弱连结超导电性.研究了弱连结超导体的 H_(c2)(T).直流磁化和 I_c(B)特性结果表明,大块 Bi_(1.4)Pb_(0.6)Sr_2Ca_2Cu_3O_y,是个弱钉扎Ⅱ类超导体,它的 H_(cl)(77K)=25Oe,且磁化曲线中有两个峰.加热实验表明,当温度升高到355K 时,样品的正常态电阻增加,零电阻超导 T_c 从107.1K 退化到99.5K.Bi1.4Pb0.6Sr2Ca2Cu3Oy oxide is a two-phase high Tc superconductor with the 110K phase to be dominant.Its zero-resistance Tc is 107.1K.The dc Meissner effect indicates a volume fraction of 8.2% for the 110K superconducting phase and 1.6% for the 85K one.The flux exclusion (dc Meissner) effect,a comparison of the upper and the lower limit superconducting volume fractions under various magneric fields along with the R(T) transitions at different magnetic fields and measuring currents show the existence of an abundance of weak link superconductivity.The temperature dependence of the Hc2 of the weak links has been studied.The dc magnetization and Ic(H) characteristics reveal that it's a weak pinning type-II super-ronductor with an Hc1 of 250e.Two peaks are present in the magnetization curve.A rise of the normal state resistance and a drop of the zero-resistance Tc from 107.1K to 99.5K were observed to occur upon heating to 355 K.

关 键 词：氧化物 超导体 弱连结 弱钉扎 

分 类 号：O511.2[理学—低温物理]