NMR study of super conducting Nb/Cu multilayrs

超导Nb/Cu多层膜的NMR研究

• 批准号: 07640490
• 负责人: KOHORI Yoh
• 金额: $ 1.54万
• 依托单位: Himeji Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640490/
• 关键词: NMR; Superconductor; Multitayr; Proximity effect

The multilayr of superconducting and normal metals, Nb/Cu, provides a good opportunity for the study of superconducivity induced by the proximity effect. NMR is especially suitable for the study of multilayrs, since it can selectively measure the thermal excitation spectra of the superconducting quasi-particles in the respecive layrs. We have carried out ^<93>Nb and ^<63>Cu NMR in Nb/Cu superconducting thin film down to 0.1K,and measured the nuclear spin lattice relaxation rate, 1/T_1, in zero field by using the field cycling method. The temperature dependence of 1/T_1 has shown that the existence of superconducting energy gap with the magnitude of 2DELTA=3.5K_BT_C for Nb layrs, and a smaller gap of about 2.8K_BT_C for Cu layrs. The 1/T_1 of ^<63>Cu measured at low temperatures has also shown the existence of the residual density of states (about 50% of the value in the normal states) in the superconducting Cu layrs. The corresponding residual density of states, even if exist, is very small in the superconducting Nb layrs.

Nb/Cu多层超导层和普通金属层的出现为研究邻近效应引起的超导性提供了良好的机会。核磁共振特别适合于多层膜的研究，因为它可以选择性地测量各层中超导准粒子的热激发谱。我们对Nb/Cu超导薄膜进行了~ <93>1 Nb和~ 1Cu<63>核磁共振，温度低至0.1K，并用场循环法测量了零场下的核自旋晶格弛豫速率1/T_1。1/T_1的温度关系表明，Nb层存在超导能隙，其大小为2DELTA=3.5K_BT_C，Cu层的超导能隙较小，约为2.8K_BT_C。在低温下测量的~（40）Cu的1/T_1<63>也表明，在超导Cu层中存在着剩余态密度（约为正常态的50%）。在超导Nb层中，即使存在相应的剩余态密度，也是很小的。

项目成果

Y. Kohori, T. Kohara, Y. Oda, M. Nishikawa, E. Kita, A. Tasaki: "^<93>Nb and ^<63>CuNMR studies of superconducting Nb/Cu multitayers" Czechoslovak Joural of Physics. 46. 743-744 (1996)

Y. Kohori、T. Kohara、Y. Oda、M. Nishikawa、E. Kita、A. Tasaki：“超导 Nb/Cu 多层的 ^<93>Nb 和 ^<63>CuNMR 研究”捷克斯洛伐克物理学杂志。

Y. Kohori, T. Kohara, Y. Oda, M. Nishikawa, E. Kita, A. Tasaki: "^<63>Cu and ^<93>Nb NMR study in Superconducting Nb/Cu multilayers" Physica B. 194-196. 2383-2384 (1994)

Y. Kohori、T. Kohara、Y. Oda、M. Nishikawa、E. Kita、A. Tasaki：“超导 Nb/Cu 多层中的 ^<63>Cu 和 ^<93>Nb NMR 研究”Physica B. 194-

Y.Kohori, T.Kohara, Y.Oda, M.Nishikawa, E.Kita, A.Tasaki: "^<63>Cu and ^<93>Nb NMR study in Super conducting Nb/Cu multilayrs" Physica B. 194-196. 2383-2384 (1994)

Y.Kohori、T.Kohara、Y.Oda、M.Nishikawa、E.Kita、A.Tasaki：“超导 Nb/Cu 多层中的 ^<63>Cu 和 ^<93>Nb NMR 研究”Physica B. 194

Y.Kohori,T.Kohara,Y.Oda,M.Nishikawa,E.Kita and A.Tasak: "^<63>Cu and ^<93>Nb NMR Study in Superconducting Nb/Cu multi layers" Physica B. 194-196. 2383-2384 (1994)

Y.Kohori、T.Kohara、Y.Oda、M.Nishikawa、E.Kita 和 A.Tasak：“超导 Nb/Cu 多层中的 ^<63>Cu 和 ^<93>Nb NMR 研究”Physica B.194