マグネタイト (Fe3O4) の圧力誘発の結晶構造とスピン状態の移行
Sheng Ju1, Tian-Yi Cai, Hai-Shuang Lu
1Department of Physics and Jiangsu Key Laboratory of Thin Films, Soochow University, Suzhou 215006, PR China. jusheng@suda.edu.cn
Journal of the American Chemical Society
|July 25, 2012
まとめ
高圧は,磁石 (Fe (((3) O (((4)) の磁気および構造的性質を大幅に変化させます. 新しい高圧相が特定され,実験結果が説明され,地球の下層マントルに磁石の存在が示唆される.
科学分野:
- 凝縮物質物理学 凝縮物質物理学
- 材料科学 材料科学とは
- 地質物理学 地質物理学とは地質物理学です.
背景:
- 高圧は,過渡金属酸化物における新興現象に極めて重要です.
- マグネタイト (Fe(3) O(4) の高圧下での振る舞いは不明であり,特にその結晶構造は不明である.
- 相関系にあるシステムにおける格子,電荷,軌道,スピンの相互作用は圧力に敏感である.
研究 の 目的:
- 第1原理の計算を用いてFe(3) O(4) の圧力誘発相変遷を調査する.
- マグネチートの高圧結晶構造に関する論争を明らかにする.
- 高圧圧縮されたFe(3) O(4) の観察された構造と磁気特性を説明してください.
主な方法:
- 第一原理 密度関数理論の計算.
- 圧力による構造変化の分析.
- 磁気モメントとFe3d軌道占有変化の調査.
主要な成果:
- 連続した構造的移行を特定した:Fd3[コンビネーション・オーバーライン]mからPbcm (29.7GPa) に,そしてBbmm (65.1GPa) に.
- 高圧段階に入ると,純磁気モメントの急激な低下が観察されました.
- Fe3d軌道再分配と結晶場の変化による65.1GPaを超える有限磁気モメントの回復を決定した.
結論:
- Fe (((3) O (((4) の高圧構造相を正確に確立した.
- 圧縮下における構造的および磁性特性の実験観察について説明します.
- 地球の下層マントルの高度に磁気化された磁石の存在を示唆した.
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
07:42Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains
Published on: July 20, 2022
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.
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...
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...
01:03Atomic Nuclei: Nuclear Spin State Overview
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of one, the...
01:23Atomic Nuclei: Nuclear Relaxation Processes
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis. This...