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Please use this identifier to cite or link to this item: http://hdl.handle.net/11178/4431

Title: MgB_2超伝導体の帯磁率とスケーリング則(電気工学科,工学部創設40周年記念号)
Other Titles: AC Susceptibilities and Scaled J_c Characteristics in MgB_2 Superconductors(DEPARTMENT OF ELECTRICAL ENGINEERING)
Authors: 北原, 一義
阿久根, 忠博
坂本, 進洋
松本, 泰國
KITAHARA, Kazuyoshi
AKUNE, Tadahiro
SAKAMOTO, Nobuyoshi
キタハラ, カズヨシ
アクネ, タダヒロ
サカモト, ノブヨシ
マツモト, ヤスクニ
九州産業大学工学研究科電気工学専攻 / 九州産業大学電気工学科 / 九州産業大学電気工学科 / 福岡大学工学部電気工学専攻
Keywords: MgB_2
Scaling Law
Irreversibility field
Issue Date: 20-Dec-2004
Publisher: 九州産業大学工学部
Abstract: From the real part χ' and the imaginary part χ" of AC susceptibilities, the essential features of fluxoid motion in superconductors are obtained. The χ' indicates the flux penetration and χ" gives the lossy component. The peak of χ" gives an information of the irreversibility field B_<irr>. AC susceptibilities were measured on powdered new superconductor MgB_2 using a SQUID magnetometer and a PPMS susceptometer at temperature range 4.5 - 40 K under DC magnetic fields up to 14 T. Powdered MgB_2 were divided into three samples with different particle size d by sieves with several mesh sizes : 45 < d < 50 μm, 50 < d < 63 μm and 75 < d < 100 μm. The critical temperatures are 38.5 K in all samples determined by the temperature dependence of magnetization under zfc and fc conditions. The AC susceptibilities are characterized from the ratio of superposed AC field amplitude and the characteristic pinning field b_p which is proportional to the pinning strength F_p. The Magnetic field and temperature dependence of the pinning strength F_p in type-II superconductors is known to be well formalized by the scaling law of the pinning force as F_p = AH^^m_<c2>(B/B_<irr>)γ(1 - B/B?<irr>)^δ, where B^<irr> is the irreversibility field, γ, δ and m are the pinning parameters. The temperature and field dependence of χ' and χ"can be numerically estimated using the scaling law and are favorably compared with the observed data of MgB_2 superconductors.
URI: http://hdl.handle.net/11178/4431
Appears in Collections:第41号

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