english

2006-4

2008/05/29(Thu) 14:07

Flux Pinning Properties of MgB2 Thin Films on Si Substrate Prepared by EBE Method

EBE法により作製したSi基板上MgB2薄膜における磁束ピンニング特性

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As-grown MgB2 thin films on Si substrates were prepared by electron-beam evaporation. The value of Jc has been enhanced by the deposition of MgB2 thin film in an O2 atmosphere. The MgB2 thin film deposited in the O2 atmosphere (O2-doped film) has exhibited the highest Jcin magnetic fields among MgB2 thin films reported before. It has been found that the high Jc of the O2-doped film is attributable to the flux pinning with grain boundaries strengthened by an introduction of MgO along grain boundaries. In a high magnetic field, a peculiar behavior of E-J characteristics where E-J curves vary in two stages was observed. This behavior also originates from the flux pinning with strengthened grain boundaries.

Grad. School of Sci. Tech., Kumamoto University: T. Fujiyoshi, M. Haruta, R. Kajita, K. Yonekura, T. Sueyoshi

Dept. of Eng., Kagoshima University: T. Doi IMR, Tohoku University: S. Awaji, K. Watanabe

電子ビーム蒸着法によってMgB2薄膜をSi基板上に作製した.酸素雰囲気中でMgB2を成膜することによりJcが向上した.この薄膜のJcは,これまで報告されたMgB2薄膜の中で最も高い.酸素雰囲気中における成膜により結晶粒界に沿ってMgOが導入され,結晶粒界による磁束ピンニングが強くなり,Jcが向上したことが明らかとなった.また,高磁場ではこの強化された結晶粒界のピンニングに起因して,2段的に変化する特徴的な電界-電流密度特性を観測した.

熊本大学大学院自然科学研究科:藤吉孝則,春田正和,梶田 龍,米倉健志,末吉哲郎
鹿児島大学工学部:土井俊哉
東北大学金属材料研究所:淡路智,渡辺和雄