鉄基層のLaO1-xFxFeAs系における超伝導性に近い磁気順序である
Clarina de la Cruz1, Q Huang, J W Lynn
1Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996-1200, USA.
Nature
|May 30, 2008
まとめ
研究者らは,鉄基超伝導体の主要な親化合物であるLaOFeAsでスピン密度波 (SDW) 順序の直接的な証拠を発見しました. ドーピングによるこの磁気秩序の抑制は,高温の銅酸化物と同様の超伝導性を促進します.
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
- マグネチズム (磁気) とは
背景:
- 高トランジション温度 (高Tc) の酸化銅は,反鉄磁気秩序に近い超伝導性を示す.
- 稀土鉄基酸化物 (ROFeAs) もドーピング時に超伝導性を示すが,親化合物の磁気秩序の直接的な証拠は欠けていた.
- 親化合物であるLaOFeAsは,磁気不安定性を示唆する異常を示しているが,スピン密度波 (SDW) 順序の直接的な証拠がない.
研究 の 目的:
- 母化合物LaOFeAs.でスピン密度波 (SDW) の磁気順序に関する直接的な実験的証拠を提供するために.
- 鉄基酸化物における構造的歪み,磁気秩序,および超伝導性の関係を調査する.
- これらの材料における超伝導性の出現における反鉄磁性の役割を理解する.
主な方法:
- 中性子散乱実験は,LaOFeAs.で実施されました.
- レジスティビティとDC磁気感受性の測定が行われました.
- フッ素ドーピングが構造的および磁性特性に及ぼす影響が研究されました.
主要な成果:
- LaOFeAsは155K以下で,四角対称から単角対称性への構造的歪みを経験する.
- 遠距離SDW型の反鉄磁気秩序は,約137K以下で発生する.
- フッ素ドーピングは,構造的歪みと磁気秩序の両方を抑制し,超伝導性につながります.
- 超伝導体制は,長距離秩序の反鉄磁性基底状態のすぐ近くにあることが判明した.
結論:
- LaOFeAsのSDW順序の直接的な証拠は,超伝導性の前駆者としてその役割を確認しています.
- 発見は,磁気と超伝導性の近さに関して,鉄ベースの超伝導体と高T (c) 銅酸化物の間の類似性を確立しています.
- この相互作用を理解することは,新しい超伝導材料の設計に不可欠です.
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