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高回転鉄のゆっくりとした磁気リラックス (II) 複合体
Danna E Freedman1, W Hill Harman, T David Harris
1Department of Chemistry and Howard Hughes Medical Institute, University of California, Berkeley, California 94720, USA.
Journal of the American Chemical Society
|January 9, 2010
まとめ
研究者らは,単分子磁石の振る舞いを示す最初の単核鉄 (II) 複合体を発見した. この複合体は,分子磁気材料の開発に不可欠な,ゆっくりとした磁気リラックスを示しています.
科学分野:
- 無機化学 無機化学とは
- マテリアルサイエンス 材料科学
- 量子物理学とは,量子物理学のことです.
背景:
- 単分子磁石 (SMM) は,高密度データストレージと量子コンピューティングの開発に不可欠です.
- 単核の移行金属複合体は,SMMの特性について積極的に研究されています.
- 磁気リラックスメカニズムを理解することは,効率的なSMMを設計するための鍵です.
研究 の 目的:
- 単一分子磁石の振る舞いを示す最初の単核移行金属複合体を報告する.
- 高回転鉄 (II) 複合体の磁気特性とリラックスダイナミクスを調査する.
- 磁気リラックスにおける量子トンネリングと応用フィールドの役割を明らかにする.
主な方法:
- トライゴナルピラミッド型の鉄 (II) 複合体 (tpa (Mes (Fe)))) の合成と特徴づけ.
- 磁気アニソトロピーを決定するためのDC磁気感受性および磁気化測定.
- AC磁気感受性測定は,変化するDCフィールド下での磁気リラックスダイナミクスを研究するために行われます.
主要な成果:
- 複合体は単一分子磁石の特性であるゆっくりとした磁気緩和を示しています.
- S = 2 の基本状態に対して,強い単軸磁性アニソトロピー (D = -39.6 cm(-1)) が決定されました.
- マグネティゼーションの量子トンネリングは,ゼロのDCフィールドで観測されました.
- 1500 OeのDCフィールドを適用すると,高温で熱的に活性化されたメカニズム,低温で温度独立のトンネリングにより,ゆっくりとした磁気放緩が開始されます.
- 磁気リラクゼーション時間は,約1500 Oeで最大を示しました.
結論:
- [tpa(Mes))Fe](-) は,単一分子磁石の性質を示す最初の単核移行金属複合体である.
- 観測された磁気リラクゼーションは,熱的に活性化されたプロセスと量子トンネリングの組み合わせによって制御され,適用されたDCフィールドの影響を受けます.
- この発見は,調節可能な性質を持つ分子磁性材料の設計に新しい道を開く.
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