掺杂的高温超导体的自旋晶格弛豫率  

SPIN-LATTICE RELAXATION IN DOPED HIGH-T_c SUPERCONDUCTORS

作　　者：冯小兵[1] 章立源[1] 

机构地区：[1]北京大学物理系

出　　处：《低温物理学报》1995年第5期348-355,共8页Low Temperature Physical Letters

基　　金：国家教委博士点基金

摘　　要：本文在赝隙和剩余态密度基础上对ＹＢａ２（Ｃｕ１－ｘＺｎｘ）３Ｏ７及Ｔｌ２Ｂａ２ＣｕＯ６＋ｙ（Ｔｃ＝４０Ｋ）在超导态下的自旋晶格弛豫行为进行了研究，在低于Ｔｃ的整个温区内计算值与实验符合较好．研究结果表明在稍低于Ｔｃ的温区赝隙导致了ＢＣＳ理论预言的相干峰的消失，而在低温（约１／２Ｔｃ以下），剩余态密度对体系的自旋晶格弛豫率的贡献起了主要作用．文中讨论了赝隙和剩余态密度的起源．通过研究还发现掺杂对体系电子结构的影响是非局域的，而且掺杂使剩余态密度有较大幅度增强，这些因素可能与掺杂强烈抑制Ｔｃ密切相关．Abstract Based on the pseudogap and the residual density of states we have studied spin-lattice relaxation rates in YBa2(Cu1-xZnx)3O7 and Tl2Ba2CuO6+y(Tc=40K)in superconducting state.In the whole temperature range below Tc the calculated values are in good accordande with the experiments.Our study indicates that the pseudogap makes the coherence peak(in the vicinity of Tc)predicted by BCS theory to disappear,and that residual density of states plays crucial role in spin-lattice relaxation at low temperatures (below about 1/2Tc).The origins of the pseudogap and residual density of states have been discussed. In additon, our resluts indicate that the dopings destroy the electronic structures of the materials not locally and the dopings caused greater increment of the residual densities of states.In our opinion,these factors may be closely related to the strong depressions of Tc caused by the dopings.

关 键 词：自旋晶弛豫 YBCO 掺杂 超导体 高TC 

分 类 号：TM263[一般工业技术—材料科学与工程] O511.1[电气工程—电工理论与新技术]