单晶GdBa_2Cu_3O_(6+δ)顺磁性和超导性的研究  

STUDY ON THE PARAMAGNETISM CAUSED BY Gd^(3+) AND SUPERCONDUCTIVITY IN SINGLE-CRYSTAL GdBd_2Cu_3O_(6+δ)SUPERCONDUCTORS

作　　者：吴高建[1] 刘胜利[1] 徐锡斌[1] 吴坚[1] 邵惠民[1] 

机构地区：[1]南京大学物理系

出　　处：《低温物理学报》2005年第A01期524-529,共6页Low Temperature Physical Letters

摘　　要：掺杂有顺磁性稀土元素离子的高温超导体的磁滞回线因包含有顺磁的贡献而变宽,使根据Bean模型得到的临界电流密度偏离了其真实的值.本文对描述其中顺磁性磁化强度贡献的扩展Brillouin函数进行了修正,并将该种描述方法应用于单晶GdBa2Cu3O6+δ样品.外场低于临界场HC1时,顺磁性对总的磁化强度没有贡献;外场高于HC1的磁场下,磁场增加和磁场降低时顺磁性的磁化贡献并不相等.由此验证了在GdBa2Cu3O6+δ的晶体结构中,超导电流沿Cu-O面流动,对位于两层Cu-O面间的顺磁性离子产生屏蔽作用.GdBa2Cu3O6+δ中超导性和顺磁性相互独立共存,超导性通过电流的屏蔽作用间接的影响了顺磁性的贡献.Magnetic measurements are performed on single-crystal GdBa2Cu3O6＋δ samples. The paramagnetism carried by the rare-earth Gd^3＋ ions in GdBa2Cu3O6＋δ is described by the extended Brillouin function with a revision. With this description, the paramagnetism at the field below Hc1 and its contribution to the total magnetization can be well explained. At the field below Hc1 the paramagnetism has no contribution to the total magnetization; at the field over Hc1 the paramagnetic magnetization has different values when in field-increasing and field-decreasing process. The width of the magnetization hysteresis loop △M is broadened by the paramagnetism. A conclusion that the electric current flows in the Cu-O planes and shields the rare-earth ions Gd^3＋ between the Cu-O planes is in accordance with the analysis. The influence of paramagnetism of Gd^3＋ ions on the magnetization critical-current density Jc based on the Bean critical-state model is also discussed.

关 键 词：顺磁性(paramagnetism) 磁滞回线(hysteresis loop) GdBa2Cu3O6+δ 

分 类 号：O511.2[理学—低温物理]