| Project/Area Number |
02650034
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
物理計測・光学
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| Research Institution | Nihon University |
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Principal Investigator |
TAKIZAWA Takeo Faculty of Humanities & Sciences, Dep. of Physics, Professor, 文理学部, 教授 (10059909)
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| Co-Investigator(Kenkyū-buntansha) |
NOMURA Shigetaka Faculty of Humanities & Sciences, Dep. of Physics, Assistant, 文理学部, 助手 (90218355)
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| Project Period (FY) |
1990 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1991: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1990: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | oxide superconductors / Y-Ba-Cu-O / quench-and-melt growth / critical current density / flux motion, flux jump / pulsed magnetic field / 酸化物高温超伝導体 / 臨界電流密度 |
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| Research Abstract |
An observation of the flux motion in a ring-shaped YBa_2Cu_3O_7 (YBCO) single crystal has been attempted under a pulsed magnetic field in a temperature range from T_c down to 20 K. The samples used were good-quality single crystals with a J_c value greater than 1X10^4 A/cm^2 at 77 K, which were made by the so-called quench-and-melt growth method (QMG). The transport critical current density (J_c) was estimated from the magnetic field where the flux just enters into the central hole of the sample ring. The value of J_c was obtained as a function of temperature. Speed of magnetic flux was also observed as a function of temperature and sample-thickness, which showed exponential dependence on temperature. At low temperatures, the flux jump was clearly observed and its interpretation was made'in terms of the traditional stabilization theory. As the thickness of a sample was made thinner, a peculiar flux motion suggesting the undulation of flux lines was observed. Though detailed analysis is now under going, we believe these experiments will give useful information on the pinning and creep mechanisms in superconductors.
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