クロミウムにおける反鉄磁気領域の進化のX線微微差分画像
P G Evans1, E D Isaacs, G Aeppli
1Bell Laboratories, Lucent Technologies, 600-700 Mountain Avenue, Murray Hill, NJ 07974, USA. pevans2@lucent.com
Science (New York, N.Y.)
|February 9, 2002
まとめ
研究者らは,磁気X線 difraktion を用いてクロミウム内の反鉄磁気ドメインをイメージした. 彼らは,スピン・フリップ・トランジションがドメイン壁から始まることを発見し,磁気相変遷の洞察を明らかにした.
科学分野:
- 凝縮物質物理学 凝縮物質物理学
- マテリアルサイエンス 材料科学
- マグネチズム (磁気) とは
背景:
- 抗鉄磁性材料は,複雑な磁気配列を示しています.
- ドメインの構造を理解することは,磁気特性を制御するために非常に重要です.
- クロミウム単一結晶は,スピン密度波の研究のためのモデルシステムです.
研究 の 目的:
- 個々の反鉄磁気スピン密度波域をクロムで視覚化するために.
- スピン・フリップ・トランジションの拡大の起源を調査する.
- ドメイン壁の振る舞いを磁気相変化と相関させるため.
主な方法:
- 磁気X線微分光学とX線焦点光学を用いた.
- 非共振磁気X線散射を用いて,スピン偏振および調節ベクトルを分析した.
- クロミウム単一結晶のミクロンスケールのイメージングを行いました.
主要な成果:
- 個々の反鉄磁気回転密度波域を成功裏に画像化しました.
- 123 Kのスピン・フリップ・トランジションがドメイン壁で始まることを決定しました.
- 移行が冷却中にこれらの壁から内側に進行することを観察し,ドメインの構造を変えることなく.
結論:
- スピン・フリップ・トランジションの拡大は,直角変調ベクトルドメインの存在に起因する.
- 磁気X線 difraktionは,ナノスケール磁気領域の振る舞いを探査するための強力なツールです.
- この発見は,反鉄磁性材料における磁気相変遷に関する新しい理解を可能にします.
関連する概念動画
01:05Atomic Nuclei: Magnetic Resonance
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...
01:10X-ray Diffraction of Biological Samples
X-ray diffraction or XRD is an analytical tool that utilizes X-rays to study ordered structures such as crystalline organic and inorganic samples, polycrystalline materials, proteins, carbohydrates, and drugs.
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal crystal...
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal crystal...
01:26Phase Contrast and Differential Interference Contrast Microscopy
Phase-Contrast Microscopes
In-phase-contrast microscopes, interference between light directly passing through a cell and light refracted by cellular components is used to create high-contrast, high-resolution images without staining. It is the oldest and simplest type of microscope that creates an image by altering the wavelengths of light rays passing through the specimen. Altered wavelength paths are created using an annular stop in the condenser. The annular stop produces a hollow cone of...
In-phase-contrast microscopes, interference between light directly passing through a cell and light refracted by cellular components is used to create high-contrast, high-resolution images without staining. It is the oldest and simplest type of microscope that creates an image by altering the wavelengths of light rays passing through the specimen. Altered wavelength paths are created using an annular stop in the condenser. The annular stop produces a hollow cone of...
01:19Magnetic Field Lines
The representation of magnetic fields by magnetic field lines is very useful in visualizing the strength and direction of the magnetic field. Each of the magnetic field lines forms a closed loop. The field lines emerge from the north pole (N), loop around to the south pole (S), and continue through the bar magnet back to the north pole.
Magnetic field lines follow several hard-and-fast rules:
Magnetic field lines follow several hard-and-fast rules:
01:24X-ray Imaging
German physicist Wilhelm Röntgen (1845–1923) was experimenting with electrical current when he discovered that a mysterious and invisible "ray" would pass through his flesh but leave an outline of his bones on a screen coated with a metal compound. In 1895, Röntgen made the first durable record of the internal parts of a living human: an "X-ray" image (as it came to be called) of his wife’s hand. Scientists worldwide quickly began their own experiments with X-rays, and by 1900, X-ray was widely...
01:26Divergence and Curl of Magnetic Field
The magnetic field due to a volume current distribution given by the Biot–Savart Law can be expressed as follows: