隙間を持つ超伝導体のインターフェースは,高温超伝導体のような振る舞いをする
C Richter1, H Boschker, W Dietsche
11] Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany [2] Experimental Physics VI, Center for Electronic Correlations and Magnetism, Augsburg University, 86135 Augsburg, Germany.
Nature
|October 8, 2013
まとめ
二次元 (2D) 超伝導体を研究すると,その状態の電子スペクトル密度が,キャリアの枯渇とともにどのように変化するかが明らかになる. 超伝導エネルギーのギャップは,キャリアの枯渇とともに増加し,高温超伝導体におけるpseudogapの振る舞いを反映しています.
科学分野:
- 凝縮物質物理学 凝縮物質物理学
- マテリアルサイエンス 材料科学
- 量子力学は,量子力学という
背景:
- 二次元 (2D) 電子系における超伝導性を理解することは,高過渡温度銅酸化物超伝導体および将来のインタフェースベースの超伝導体にとって極めて重要です.
- これらのシステムにおけるキャリア枯渇時の状態のスペクトル密度のような基本的な超伝導パラメータの振る舞いは,まだ十分に理解されていません.
研究 の 目的:
- キャリア密度の関数として2D超伝導体内の状態の電子スペクトル密度の変化を実験的に調査する.
- 2D電子系において,電荷载体が枯渇したときに超伝導パラメータがどのように進化するかを明らかにする.
主な方法:
- 平面交差点を持つトンネルスペクトロスコピーを利用して,状態の電子スペクトル密度を測定しました.
- 導電性LaAlO3-SrTiO3インターフェイスを,電ゲートフィールドによって制御される,調節可能な2D超伝導体として採用した.
主要な成果:
- Bardeen-Cooper-Schrieffer超伝導ギャップ関数と一致する状態の密度において,約40マイクロ電子ボルトのエネルギーギャップを観測した.
- 超伝導のギャップは,ドーピング不足地域とドーピング過剰地域の両方で,充電キャリアの枯渇とともに増加することが判明しました.
- この行動は,キャリア密度に対する臨界温度のドーム状の依存と対照的です.
結論:
- キャリア枯渇による超伝導ギャップの観測された増加は,高移行温度銅酸化物超伝導体における擬似ギャップの行動に類似しています.
- これらの発見は,超伝導的ギャップから偽ギャップのような行動へのスムーズな移行が,2D超伝導性の一般的な特徴である可能性があることを示唆しています.
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