TY - JOUR
T1 - Superconducting proximity effect in niobium/graphite complex systems
AU - Kubo, Toshiharu
AU - Ohashi, Yoshiko F.
AU - Kinoshita, Takeshi
AU - Terai, Takayuki
N1 - Funding Information:
We are indebted to Prof. Y. Kaburagi of Musashi Institute of Technology for kindly supplying a precious KG crystal. We would thank K. Kitamura for his help in evaporation of Nb films. A part of this work was supported by Keio Gijuku Academic Development Funds, and the author was supported through the 21st Century COE Program, “Mechanical Systems Innovation,” by the Ministry of Education, Culture, Sports, Science and Technology.
PY - 2007/9/1
Y1 - 2007/9/1
N2 - In the junction of a superconductor (S) and a normal conductor (N), the superconducting proximity effect arises, and the transition temperature (Tc) and critical field (Hc) of S/N bilayer usually lower from those in the superconductor itself (Tcs, Hcs). However, in the niobium/graphite corresponding to S/N bilayers, it was found by the authors that the ratio Tc* / Tcs showed a periodic characteristics with kish graphite (KG) film thickness (dKG) and the peak values of the ratio exceeded 1.00 where niobium (Nb) film thickness (dNb) was 40 nm. In this study, we studied experimentally the relation between Tc* and dKG under some conditions of dNb 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 Tc* / Tcs vs. dKG showed a periodic characteristics at all dNb in this study, and it is indicated that the larger interference effect can be observed under certain condition of dNb and dKG.
AB - In the junction of a superconductor (S) and a normal conductor (N), the superconducting proximity effect arises, and the transition temperature (Tc) and critical field (Hc) of S/N bilayer usually lower from those in the superconductor itself (Tcs, Hcs). However, in the niobium/graphite corresponding to S/N bilayers, it was found by the authors that the ratio Tc* / Tcs showed a periodic characteristics with kish graphite (KG) film thickness (dKG) and the peak values of the ratio exceeded 1.00 where niobium (Nb) film thickness (dNb) was 40 nm. In this study, we studied experimentally the relation between Tc* and dKG under some conditions of dNb 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 Tc* / Tcs vs. dKG showed a periodic characteristics at all dNb in this study, and it is indicated that the larger interference effect can be observed under certain condition of dNb and dKG.
KW - Andreev reflection
KW - Graphite
KW - Niobium
KW - Proximity effect
KW - Superconductor
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U2 - 10.1016/j.physc.2007.03.202
DO - 10.1016/j.physc.2007.03.202
M3 - Article
AN - SCOPUS:34548158986
SN - 0921-4534
VL - 460-462 II
SP - 1013
EP - 1014
JO - Physica C: Superconductivity and its applications
JF - Physica C: Superconductivity and its applications
IS - SPEC. ISS.
ER -