3次元的に配置された磁気モーメントを備えた単一成分分子導体 [Cu(dmdt) 2],結合された電気と磁気移行を示す
Biao Zhou1, Yuki Idobata, Akiko Kobayashi
1Department of Chemistry, College of Humanities and Sciences, Nihon University, Setagaya-Ku, Tokyo, Japan.
Journal of the American Chemical Society
|July 5, 2012
まとめ
この研究では,分子導体 [Cu ((dmdt) 2 ] を調査し,導電電子と磁気モメントのユニークな共存を明らかにしました. 導電状態から95K近くの絶縁状態へと移行し,同時に電気的および反鉄磁的変化を起こします.
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
- 固体化学 固体化学
背景:
- 単一コンポーネント分子導体は,電子と磁気特性の相互作用を研究するためのプラットフォームを提供します.
- 分子 [Cu(dmdt) 2 (dmdt = dimethyltetrathiafulvalenedithiolate) は,π伝導電子と磁気モメントを統合しています.
- このような材料の相変化を理解することは,新しい電子機器やスピントロニックデバイスの開発に不可欠です.
研究 の 目的:
- [Cu(dmdt) 2]結晶の電気および磁気特性を調査する.
- 導電性,磁気順序,構造変遷の関係を決定する.
- 高圧が観測された相変遷に及ぼす影響を調査する.
主な方法:
- [Cu ((dmdt) 2) ]単結晶の合成と特徴づけ.
- 温度に依存する抵抗性と磁気感受性の測定.
- 電子スピン共振 (ESR) スペクトロスコーピー.
- 低温でのX線結晶学. 低温でのX線結晶学.
- 分子構成の計算分析. 分子構成の計算分析. 分子構成の計算分析. 分子構成の計算分析. 分子構成の計算分析. 分子構成の計算分析. 分子構成の計算分析. 分子構成の計算分析.
- ダイヤモンド・アンビル・セルを使った高圧抵抗性測定.
主要な成果:
- [Cu(dmdt) 2]は室温伝導率110 S cm(-1) を示し,金属的性質が弱い.
- 隔離状態への移行は95K近くで起こり,同時に電気と反鉄磁石のオーダーリングが伴います.
- 磁気感受性は,100〜300 Kのキュリー・ワイス行動 (C = 0.375 emu/mol, Θ = 180 K) に従っている.
- 高圧 (3.3 GPa) は,環境圧で観測される絶縁変換を抑制する.
- 形状分析は,リガンドと酸化状態が分子構造に依存していることを明らかにします.
結論:
- [Cu ((dmdt) 2) ]の結晶構造は,導電電子と3D磁気モメントの共存を容易にする.
- 電気と反鉄磁性の同時移行は,環境圧で95K近くで起こります.
- 高圧は電子と磁気相の振る舞いを大きく変化させ,絶縁変換を抑制する.
関連する概念動画
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:26Diamagnetism
Materials consisting of paired electrons have zero net magnetic moments. However, when these materials are placed under an external magnetic field, the moments opposite to the field are induced. Such materials are called diamagnets. Diamagnetism is the response of the diamagnets when placed in an external magnetic field.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
01:31Ferromagnetism
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
01:30Paramagnetism
Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly oriented, and thus the net moment is zero. Under an external field, a torque acting on the moments tends to align them along the field's direction. However, the random thermal motion of electrons produces a torque opposite to the external field and tries to disorient the moments. These two competing effects align only a few moments along the...
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...