関連する実験動画
Updated: May 8, 2026
12:20
Sputter Growth and Characterization of Metamagnetic B2-ordered FeRh Epilayers
Published on: October 5, 2013
BaFe2 (((PO4) 2における構造的な再入力の移行を通して:二次元の鉄磁性の影響
Rénald David1, Alain Pautrat, Dmitry Filimonov
1Université Lille Nord de France, UCCS, UMR-CNRS 8181, ENSCL-USTL, Villeneuve d'Ascq, France.
Journal of the American Chemical Society
|August 24, 2013
まとめ
バリウム鉄酸化物,BaFe2(PO4) 2は,最初の2D Ising 鉄磁性酸化物である. それは,磁気順序とヤーン・テラー不安定によって駆動される,キュリー温度に近いユニークな再エントラント構造的移行を示しています.
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
- マグネチズム (磁気) とは
背景:
- 二次元 (2D) 材料は,縮小された次元性によりユニークな物理的特性を提供します.
- マグネティック・オーダーリングの酸化物質は,スピントロニックのアプリケーションにとって重要な関心があります.
- オキシド中の鉄磁気は珍しいため,新しい発見は非常に価値があります.
研究 の 目的:
- BaFe2(PO4)2を2Dの新型鉄磁性酸化物として合成し,特徴づけること.
- BaFe2 ((PO4) 2.2) の構造的および磁気的相変遷を調査する.
- 結晶構造,ヤーン・テラー歪み,磁気特性との相互作用を理解する.
主な方法:
- 材料の準備のための水熱合成.
- クリスタル構造の決定のためのX線 difraktion.
- モースバウアー光譜法と電子パラマグネティック共鳴法 (EPR) を用いて磁気特性を決定する.
- エネルギー推定のための密度関数理論 (DFT) 計算.
主要な成果:
- BaFe2(PO4)2は,FeO6オクターエドルのハネコム層を持つ最初の2Dアイジング鉄磁性酸化物として特定されました.
- 140K以下では,Jahn-Tellerの不安定性により,トリゴナルからトリクリニック (P-1) への構造的移行が起こります.
- ~70K以下で観察されたトリゴナル (R-3) への希少な再侵入構造的移行は,鉄磁気順序 (Tc = 65.5K) と一致しています.
- モッズバウアー光譜法により,四極分裂の不連続の変化が明らかにされ,構造的移行と相関していた.
- EPRは,単軸磁性アニソトロピーとTc.以上の磁域の存在を確認した.
結論:
- BaFe2(PO4)2は,ヤーン-テラー歪みと2Dイッシングの鉄磁力学との複雑な相互作用を示しています.
- リエントラント構造的移行は,磁気秩序と結びついたユニークな現象です.
- この材料は,酸化物における2Dイジング磁性を研究するためのモデルシステムとして機能します.
さらに関連する動画
09:06Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope
Published on: March 24, 2019
08:55Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
関連する概念動画
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...
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...
03:24Hybridization of Atomic Orbitals I
The mathematical expression known as the wave function, ψ, contains information about each orbital and the wavelike properties of electrons in an isolated atom. When atoms are bound together in a molecule, the wave functions combine to produce new mathematical descriptions that have different shapes. This process of combining the wave functions for atomic orbitals is called hybridization and is mathematically accomplished by the linear combination of atomic orbitals. The new orbitals that...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
02:57Coordination Number and Geometry
For transition metal complexes, the coordination number determines the geometry around the central metal ion. Table 1 compares coordination numbers to molecular geometry. The most common structures of the complexes in coordination compounds are octahedral, tetrahedral, and square planar.
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.