超伝導性MgB2薄膜における高臨界電流密度と強化された不可逆性フィールド
1Department of Materials Science and Engineering, University of Wisconsin, Madison, Wisconsin 53706, USA. eom@engr.wisc.edu
Nature
|June 1, 2001
まとめ
酸素合金マグネシウムジボリド (MgB2) の薄膜は,高場超伝導性が強化されています. この突破は,先端の磁石と電子機器の潜在能力を提供し,重要な磁場における以前の制限を克服します.
科学分野:
- マテリアルサイエンス 材料科学
- 凝縮物質物理学 凝縮物質物理学
背景:
- マグネシウムジボリド (MgB2) は39Kで超伝導性を示し,超伝導材料の新しいクラスを提供している.
- MgB2は,Nb3SnやNb-Ti.のような従来の超伝導体よりも高い移行温度を持っています.
- MgB2の限界は,その控えめな不可逆性場 (H*) で,実用的な応用が制限されています.
研究 の 目的:
- MgB2薄膜の超伝導特性に対する酸素合金の影響を調査する.
- 高フィールドのアプリケーションのためのMgB2の不可逆性フィールド (H*) と臨界電流密度を高めるために.
主な方法:
- 酸素と合金されたMgB2薄膜の製造.
- 逆行不可能なフィールドの温度依存度 (H * T) の測定.
- 様々な磁場と液体ヘリウム温度 (4.2 K) での臨界電流密度の評価.
主要な成果:
- 酸素合金MgB2薄膜は,散発MgB2と比較して,より急なH*(T) 温度依存を示しています.
- 4.2Kで14Tを超える不可逆性フィールド (H*) が達成されました.
- 高い臨界電流密度が実証されました: 1 T で 1 MA cm-2 と 10 T で 105 A cm-2.
結論:
- 酸素合金により,MgB2.2の高場超伝導性能が著しく向上する.
- 改造されたMgB2薄膜は,高電場超伝導磁石および電子アプリケーションの大きな可能性を示しています.
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