カニオン・ディアブロの隕石から発見されたグラファイトの結節の鉄磁性
J M D Coey1, M Venkatesan, C B Fitzgerald
1Physics Department, Trinity College, Dublin 2, Ireland. jcoey@tcd.ie
Nature
|November 15, 2002
まとめ
隕石石のグラファイトは強い鉄磁気性を表しており,その発見は磁気的近接効果を示唆している. この研究は,不純物を超えて,炭素材料における磁性の起源を探求しています.
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
- 地質化学 地質化学
背景:
- 最近の研究では,グラファイトと合成炭素材料の弱い鉄磁性について報告しています.
- 炭素の不純物質の影響から固有の鉄磁性を区別することは,弱い信号のために困難です.
研究 の 目的:
- 新しい実験的アプローチを用いて,グラフィート材料における鉄磁性の起源を調査する.
- 隕石のサンプルで観測された磁気に対する grafite 対 不純物の貢献を決定する.
主な方法:
- カニオン・ディアブロの隕石から採取した地球外の10個のグラフィットサンプルを分析した.
- 鉱物含量と磁化量を定量化するための相組成分析.
主要な成果:
- 隕石から採取したグラファイトのサンプルには,室温で強い鉄磁気性が示された.
- 鉄に富んだ鉱物 (磁石,カマサイト) が磁化量の約3分の2を占めた.
- 残りの磁気化は,石墨と関連しており,炭素原子あたり平均0.05ボールの磁性子を示した.
- 磁気配列温度が570K近くで観測されました.
結論:
- 隕石石のグラファイットの鉄磁性は,鉄に富んだ不純物によるだけではない.
- そのメカニズムとして,グラファイトとミネラルインクルージョンの接点における磁性近接効果が提案されている.
- この発見は,炭酸性物質の磁気性についての洞察を提供します.
関連する概念動画
Network Covalent Solids
12.9K
Network covalent solids contain a three-dimensional network of covalently bonded atoms as found in the crystal structures of nonmetals like diamond, graphite, silicon, and some covalent compounds, such as silicon dioxide (sand) and silicon carbide (carborundum, the abrasive on sandpaper). Many minerals have networks of covalent bonds.
To break or to melt a covalent network solid, covalent bonds must be broken. Because covalent bonds are relatively strong, covalent network solids are typically...
To break or to melt a covalent network solid, covalent bonds must be broken. Because covalent bonds are relatively strong, covalent network solids are typically...
12.9K
Magnetism
8.2K
Magnets are commonly found in everyday objects, such as toys, hangers, elevators, doorbells, and computer devices. Experimentation on these magnets shows that all magnets have two poles: one is labeled north (N) and the other south (S). Magnetic poles repel if they are alike and attract if unlike. Moreover, both poles of a magnet attract unmagnetized pieces of iron.
An individual magnetic pole cannot be isolated. No matter how small, every piece of a magnet contains a north pole and a south...
An individual magnetic pole cannot be isolated. No matter how small, every piece of a magnet contains a north pole and a south...
8.2K
Diamagnetism
2.8K
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....
2.8K
Ferromagnetism
2.8K
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...
2.8K
Paramagnetism
2.4K
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...
2.4K
Potential Due to a Magnetized Object
924
Magnetic dipoles in magnetic materials are aligned when placed under an external magnetic field. For paramagnets and ferromagnets, dipole alignment occurs in the direction of the magnetic field. However, the dipoles align opposite to the field in the case of diamagnets. This state of magnetic polarization due to the external field is called magnetization. Magnetization is defined as the dipole moment per unit volume. It plays a similar role to polarization in electrostatics.
The vector...
The vector...
924


