イルメニット・ヘマチット鉱物におけるアンチフェーズ領域と逆熱持続磁気
Science (New York, N.Y.)
|September 18, 1981
まとめ
合成イルメニット・ヘマタイトには,反相ドメインと境界線が含まれています. 高温サンプルで観測されるこれらの境界線の高密度は,逆熱超常磁性を得る上で極めて重要です.
科学分野:
- ミネラル物理学 ミネラル物理学
- 地磁気学とは地磁気学です.
背景:
- イルメニット-ヘマタイトの固体溶液は,古磁気学において重要である.
- その磁気特性を理解するには,その微細構造を調べる必要があります.
研究 の 目的:
- 合成イルメニット・ヘマタイトの微細構造を調査するために.
- 微細構造と磁気特性の関係を決定するために,特に逆熱磁気磁気.
主な方法:
- トランスミッション電子顕微鏡 (TEM) を用いて,合成イルメニット・ヘマチットサンプルを検査した.
- 試料は,異なる温度 (1300°Cと900°C) から消火されました.
- 熱性磁気性を含む磁気特性は,磁場での冷却後に測定されました.
主要な成果:
- トランスミッション電子顕微鏡では,合成イルメニット・ヘマタイトで初めて,明確に定義された反相領域と境界を明らかにした.
- 1300°Cで消火したサンプルは,ドメイン境界の高密度を示した.
- 900°Cで消火したサンプルは,ドメイン境界の密度が著しく低いことを示した.
- ドメイン境界の密度が高いサンプルのみ,磁場で冷却したときに逆熱耐磁性を獲得した.
結論:
- 反相ドメインと境界の存在は,合成イルメニット・ヘマチットにおける重要な微細構造的特徴である.
- これらのドメイン境界の高密度は,この鉱物系における逆熱磁気磁力の獲得に必要な条件である.
関連する概念動画
01:27Magnetic Fields
A moving charge or a current creates a magnetic field in the surrounding space, in addition to its electric field. The magnetic field exerts a force on any other moving charge or current that is present in the field. Like an electric field, the magnetic field is also a vector field. At any position, the direction of the magnetic field is defined as the direction in which the north pole of a compass needle points.
A magnetic field is defined by the force that a charged particle experiences...
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01:19Magnetic Field Lines
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Magnetic field lines follow several hard-and-fast rules:
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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.
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01:31Ferromagnetism
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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...
01:31Magnetic Susceptibility and Permeability
In linear magnetic materials, like paramagnets and diamagnets, magnetization is proportional to the magnetic field intensity. The constant of proportionality, a dimensionless number, is called magnetic susceptibility. The value of the susceptibility depends on the type of material.
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...