Superconducting proximity effect in niobium/graphite complex systems

✍ Scribed by Toshiharu Kubo; Yoshiko F. Ohashi; Takeshi Kinoshita; Takayuki Terai

• Book ID: 104083000
• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 161 KB
• Volume: 460-462
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/j.physc.2007.03.202

✦ Synopsis

In the junction of a superconductor (S) and a normal conductor (N), the superconducting proximity effect arises, and the transition temperature (T c ) and critical field (H c ) of S/N bilayer usually lower from those in the superconductor itself ðT s c ; H s c Þ. However, in the niobium/graphite corresponding to S/N bilayers, it was found by the authors that the ratio T Ã c =T s c showed a periodic characteristics with kish graphite (KG) film thickness (d KG ) and the peak values of the ratio exceeded 1.00 where niobium (Nb) film thickness (d Nb ) was 40 nm. In this study, we studied experimentally the relation between T Ã c and d KG under some conditions of d Nb in order to investigate the superconductivity of niobium/graphite bilayers in detail. As in the case of previous study, thin KG films of various thickness ranging from 20 to 160 nm were prepared. For making a specimen, Nb was deposited on a KG film and a quartz glass substrate simultaneously. Nb film thickness prepared in this study were 27 nm, 40 nm and 47 nm. Each resistance of Nb and Nb/KG films was measured at the same time. As the result, it was found that the ratio T Ã c =T s c vs. d KG showed a periodic characteristics at all d Nb in this study, and it is indicated that the larger interference effect can be observed under certain condition of d Nb and d KG .