| Project/Area Number |
18510090
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Nanostructural science
|
|---|
| Research Institution | Tohoku University |
|---|
Principal Investigator |
EBISAWA Hiromichi Tohoku University, professor emerittus (90005439)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
HAYASHI Masahiko Akita University, Faculty of Education and Human Studies, Associate Professor (60301040)
瀧澤 剛 東北大学, 大学院情報科学研究科, 技術補佐員 (80361161)
|
|---|
| Project Period (FY) |
2006 – 2007
|
| Project Status |
Completed (Fiscal Year 2007)
|
| Budget Amount *help |
¥4,150,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥450,000)
Fiscal Year 2007: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Fiscal Year 2006: ¥2,200,000 (Direct Cost: ¥2,200,000)
|
|---|
| Keywords | exotic superconductor / high Tc superconductor / multiple Josephson junction / scanning SQUID microscope / topological crystals / phase defects / nano-scale superconductor / noise reduction / 多重ジョゼフソン効果 / ナノ超伝導 / 超伝導ゆらぎ |
|---|
| Research Abstract |
Aiming to develop a frontier of novel physics in nano-scale exotic superconductors, several studies have been advanced.
(1) Numerical studies on multiple Josephson junctions in d-wave high-Tc superconductors: By numerically solving differential equations describing the time evolution of the phase differences, we have observed that the localized oscillation modes, which correspond to the breather modes in sine-Gordon equation, causes a non-zero voltage in superconducting state, thus driving the transition to resistive state. These modes actually work as "seeds" inducing the transition.
(2) A procedure to improve the resolution of the images of scanning SQUID microscope is studied, which is useful in observing the magnetic field distribution in d-wave/s-wave (or p-wave/s-wave) hybrid superconducting systems. In order to minimize the effects of noise and finite coil size, numerical simulation is advanced and comparison with experiments is made. The difficulty in application to images with non-zero magnetic field near the edges has been overcome with the help of the simulations.
(3) To exemplify of the effects of sample geometry, we have studied the distribution of dislocations in tiny ring-shaped crystals and found several different dislocation distributions. To be more precise, ring-shaped topological crystals of NbSe3 etc. are studied within linear elastic theory. The uniform distribution of dislocations in crystals with circumferences larger than 1 micron is predicted. Below this size, the destruction of elastic coupling can take place.
(4) The effects of superconducting fluctuations in the conductivity of tiny superconducting networks are studied. Under an AC current noise, a Shapiro-step-like structure appears in the current-voltage characteristics of current-biased system, causing an anomalous nonlinear resistivity.
|
