2006 Fiscal Year Final Research Report Summary
Magneto-optical study on control and dynamics of magnetic flux quanta
| Project/Area Number |
16360033
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied optics/Quantum optical engineering
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| Research Institution | Osaka University |
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Principal Investigator |
MURAKAMI Hironaru Osaka University, Institute of Laser Engineering, Associate professor, レーザーエネルギー学研究センター, 助教授 (30219901)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Faraday Effect / Magneto-optical microscope / high-Tc superconductor / magnetic flux quanta / Abrikosov lattice / rare earth iron garnet / laser / superconductor device |
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| Research Abstract |
1. We have developed a homemade magneto-optical (MO) microscope system and succeeded in the observation of the magnetic flux quantum distribution in high-Tc superconductor BSCCO(2212) single crystals.
2. We have succeeded in the observation of the Abrikosov lattice-like structures of magnetic flux quanta in the single crystals grown by LPE method. On the other hand, a-axis aligned distribution of magnetic flux quanta was reproducibly observed in the single crystals grown by TSFZ method, probably due to some extrinsic defects introduced in the crystal growth.
3. We have prepared Bi, Ga substituted iron garnet by the metal organic decomposition method, and optimized its characteristics as a MO indicator. It was found out that the highest sensitive indicator can be obtained for the garnet film with the thickness of about 1.4 μm.
4. We have developed a laser scanning MO imaging system which has a spatial resolution less 0.5 μm. In order to check the performance, we have carried out a series of experiments by using superconducting flux flow type devices of YBCO, and succeeded in the dynamic observation of the magnetic field generated around the control line applied with bias current. It was also confirmed that the magnetic sensitivity of the system is as good as several μT (tesla) in a quasi static magnetic field condition, and several 10 μT in a dynamic observation mode. This result shows that the developed system has an enough sensitivity to dynamically detect the magnetic flux quantum in superconducting devices.
5. We fabricated Josephson vortex flow transistors with a parallel array of Josephson junctions, and succeeded in the observation of clear modulations of critical current and the flow voltage by applying DC current to the control current line or by illuminating modulated femtosecond optical pulse to the Josephson junctions.
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