YBCO薄膜中自旋极化准粒子的注入效应  

SPIN-POLARIZED QUASIPARTICLE INJECTION EFFECT IN YBCO FILM

作　　者：曹春海[1] 杨名[1] 张世远[2] 杨森祖[1] 崔旭高[2] 尤立星[1] 吉争鸣[1] 康琳[1] 许伟伟[1] 

机构地区：[1]南京大学电子科学与工程系,南京210093 [2]南京大学物理系,南京210093

出　　处：《低温物理学报》2003年第3期168-173,共6页Low Temperature Physical Letters

基　　金：国家重点基础研究发展规划项目 (G19990 6 4 6和 0 0 1CB6 10 6 0 3);国家高技术研究发展计划资助的课题~~

摘　　要：采用Nd0 .7Sr0 .3MnO3/SrTiO3/YBa2 Cu3O7-δ的异质结构 ,研究了自旋极化准粒子的注入效应 .在 5 6 μm宽的YBCO膜条上成功地制备了与超导膜条同样宽度但不同长度的六个注入结区 ,长度L分别为 80 μm ,4 0 μm ,2 0 μm ,10 μm ,5 μm和 2 μm .80nm厚的YBCO薄膜在 16K温度下Jc 为 2× 10 5A/cm2 .Iin=0 .5mA的自旋电流注入下 ,随L从 80 μm逐渐顺次减小时 ,注入效率 η =ΔJc/ΔJin逐渐增大 .而当L≤ 2 0 μm后 ,η不再增加 ,达到几乎相同的值 (～ 6 ) .初步分析认为这与自旋极化准粒子在超导膜内的有效自旋扩散长度有关 .异质结构中YBCO薄膜的超导电性以及注入窗口的尺寸对获得大的自旋注入效率十分重要 .Spin-polarized quasiparticle injection effect into YBCO film with Nd-{0.7}Sr-{0.3}MnO-3/SrTiO-3/YBa-2Cu-3O-{7-δ} heterostructures has been studied. Six injection windows have same width of 56μm, but have different length L as 80μm, 40μm, 20μm, 10μm, 5μm and 2μm, respectively. J-c of 80nm YBCO film strip is 2×105A/cm2 at 16K. Under the spin-polarized injection current of I-{in}0.5mA, the injection efficiency ηΔJ-c/ΔJ-{in} increases when L decreases from 80μm, and when L≤20μm, η hardly varies and reaches up to 6. By the primary analysis, we think these results relate with the effective spin diffusion length of spin-polarized quasiparticles in HTS thin film. It is important to keep good superconducting characteristic of YBCO film in the heterostructures and to select suitable sizes of injection windows for relatively high spin-injection efficiency.

关 键 词：YBCO薄膜 自旋极化准粒子 准粒子注入效应 异质结构 高温超导体 

分 类 号：O511.4[理学—低温物理]