巨大な磁気弾性効果が,Ba3BiIr2O9におけるスピンギャップの開口に起きました
Wojciech Miiller1, Maxim Avdeev, Qingdi Zhou
1School of Chemistry, The University of Sydney, Sydney 2006, Australia.
Journal of the American Chemical Society
|February 3, 2012
まとめ
この研究は,5次元移行金属化合物であるBa3BiIr2O9に巨大な磁気弾性効果があることを明らかにしています. この珍しい現象は,スピンギャップの開口と原子距離の大きな変化に関連しています.
科学分野:
- マテリアルサイエンス 材料科学
- 固体物理 固体物理学
- 量子マグネティズム 量子マグネティズムとは
背景:
- 4dおよび5d移行金属は,分散的バレンスの軌道を有し,磁気弾性などの量子協同現象を希少にします.
- マグネト弾性 (磁気と弾性の性質の結合) は,新しい物質の振る舞いを理解する上で極めて重要です.
研究 の 目的:
- 5d移行金属化合物における磁気弾性性の発生を調査する.
- Ba3BiIr2O9のユニークな性質と量子協力効果の可能性を特徴づける.
主な方法:
- 6Hペロブスキート Ba3BiIr2O9.9の合成と構造的特徴づけ
- マグネティック・トランジションとスピン・ギャップ・オープニングを特定するための磁気感受性測定.
- マグネト弾性効果を定量化するための膨張計と熱膨張測定.
主要な成果:
- Ba3BiIr2O9は巨大な磁気弾性効果を示しており,5d化合物で観測された最大のものです.
- T* = 74 Kで,スピン・ギャップの開口によって特徴づけられる,第1次相変遷が発生します.
- この移行は,Ir-Ir距離が4%増加し,熱体積が1%拡大することを意味する.
結論:
- 観測された巨大な磁気弾性効果は,直接のIr-Ir結合とIr-O-Ir磁気超交換の競争によって引き起こされる.
- Ba3BiIr2O9は5次元移行金属化合物の量子協同現象を研究するためのモデルシステムとして機能しています.
- この発見は,調節可能な磁気弾性特性を有する材料を設計するための新しい道を開きます.
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