圧力下にある重原子鉄磁石:構造の変化と磁気反応
Masaki Mito1, Yuki Komorida, Hideki Tsuruda
1Faculty of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550 Japan.
Journal of the American Chemical Society
|October 23, 2009
まとめ
フェロ磁性材料に物理的な圧力をかけると,磁性特性が変化します. 圧力の増加は当初,鉄磁気配列の温度を高めますが,さらに圧縮すると,分子堆積の変化により温度が下がります.
科学分野:
- 材料科学 材料科学とは
- 凝縮物質物理学 凝縮物質物理学
- オーガニック・エレクトロニクス
背景:
- 鉄磁性有機材料は,新しい電子アプリケーションの可能性を秘めています.
- 分子堆積は,そのような材料の磁気特性に大きな影響を与える.
- 圧力に依存する振る舞いを理解することは,材料設計において極めて重要です.
研究 の 目的:
- フェロ磁性ビスディセレナゾリル基の磁気配列に対する物理的圧力の影響を調査する.
- ピ・スタック・スリップの変化を,鉄磁気順序温度 (T (C)) と相関させる.
主な方法:
- 1GPaまでの水静圧を適用する.
- 変圧下での鉄磁気配列温度 (T (C)) の測定.
- 施された圧力に対する反応として,pi-stackの滑り方の分析.
主要な成果:
- 物理的な圧力は,鉄磁性ビスディセレナゾリル基のpi-stackの滑り方を減少させます.
- 鉄磁気配列温度 (T ((C)) は,最初は圧力とともに上昇し,1GPa近くで最大21Kに達する.
- 1 GPaを超える圧力では,pi-stack がより重複するにつれて,T (C) が減少します.
結論:
- 分子配列の圧力による変化は,磁気配列温度に直接影響を及ぼします.
- 圧力を最適化することは,これらの有機材料の鉄磁性特性を最大化するための鍵です.
- この研究は,有機根性鉄磁石の圧力依存磁性についての洞察を提供します.
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
Ferromagnetism
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...
Paramagnetism
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...
Magnetic 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...
Atomic 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...
Diamagnetism
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.
Atomic 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...
