関連する実験動画
Updated: Jun 16, 2025

12:20
Sputter Growth and Characterization of Metamagnetic B2-ordered FeRh Epilayers
Published on: October 5, 2013
14.6K
高エントロピーは,高度に乱れたスピネルフェリットの鋭い磁気移行を保護した
Lujin Min1,2, John P Barber3,4, Yu Wang1,5
1Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, United States.
Journal of the American Chemical Society
|August 20, 2024
まとめ
高エントロピーのオキシドは,高乱れで,鋭い磁気移行を示す. 単一結晶を合成すると ランダムな元素分布が明らかになり 均一性が保たれ 磁気順序が保たれ 新しい研究の道が開きます
科学分野:
- 材料科学
- 凝縮物質物理学
- 固体化学
背景:
- 材料の磁気配列に 障害が及ぼす影響を調査することは極めて重要です
- 高エントロピー酸化物 (HEO) は極度の乱密度を示し,磁気行動を複雑にします.
- 高品質の単結晶が不足しているため,HEO組成障害の影響に関する深い調査が制限されています.
研究 の 目的:
- 高品質の単結晶高エントロピースピネルフェライトを合成する.
- HEOにおける磁気移行に対する組成障害の影響を調査する.
- HEOにおける元素分布と磁気順序の関係を理解する.
主な方法:
- 高エントロピー単結晶スピネルフェライト (Mg0.2Mn0.2Fe0.2Co0.2Ni0.2) Fe3-xO4の合成
- 高温磁化測定について
- ニュートロン偏光実験
- 拡張X線吸収微細構造 (EXAFS) 測定
主要な成果:
- 748 K (x=1),694 K (x=1.5),674 K (x=1.8) で観測されたフェリ磁気移行.
- 磁気移行は,Fe3O4とは異なり,x=1とx=1.5の最小の拡大を示した.
- EXAFSはランダムな要素分布を明らかにし,局所的なクラスターと短距離注文を減らしました.
- 試料の均質性が向上し,結合長さの変動にもかかわらず,鋭い磁気移行が保存されます.
結論:
- 長い距離の磁性を持つ最初のHEO単体結晶の合成に成功しました.
- HEOのランダムな元素分布は均一性を高め,磁気移行を鋭くする.
- HEOにおける高構成エントロピーと磁気順序の相互作用が実証された.
- 磁気高エントロピーの酸化物の研究と応用のための新しい道を開いた.
関連する概念動画
Ferromagnetism
2.4K
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...
2.4K
Colors and Magnetism
11.6K
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...
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...
11.6K
Paramagnetism
2.5K
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...
2.5K
Atomic Nuclei: Nuclear Spin State Overview
903
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...
903
Atomic Nuclei: Nuclear Spin State Population Distribution
962
Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.
962
Atomic Nuclei: Nuclear Relaxation Processes
632
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.
632

