物質の極端な状態に対する負のプアソン比
1Honeywell International, Honeywell Technology Center, Morristown, NJ 07962-1021, USA. Departamento de Fisica, Universidade Federal de Juiz de Fora (UFJF), Juiz de Fora, 36036-330, Mina Gerais, Brazil. Department of Physics and Measurement Technolo.
まとめ
科学者たちは,伸縮時に膨張する物質を発見し,これを負のポアソン性質と呼びました.
科学分野:
- マテリアルサイエンス 材料科学
- 天体物理学 天体物理学
- 凝縮物質物理学 凝縮物質物理学
背景:
- 材料は,通常,伸縮すると横向に収縮します (ポジティブなポアソン比率).
- 負のポアソンの比率 (アクセティックな行動) は,理論的に様々な結晶構造で予測されます.
- アクセティック材料の理解は,高度な応用と天体物理学現象にとって極めて重要です.
研究 の 目的:
- 特定の結晶系における負のプアソンの比率を予測し,実験的に実証する.
- 極度の天体物理環境における大きなプアソンの比率の影響を調査する.
- フォトニックデバイスにおける補助物質の潜在的な応用を調査する.
主な方法:
- ボディ・センター・キュービック (BCC) 段階および他の結晶タイプの理論的予測.
- 低密度トラップされたイオン結晶を用いた実験デモ.
- 高張力キュロンビック光子結晶の分析.
主要な成果:
- ネガティブなポアソンの比率は,白矮星や中性子星に関連するBCC相について予測されています.
- 実験的証拠は,閉じ込められたイオン結晶の補助的振る舞いを確認しています.
- 巨大陽性と負のポアソンの比率は,張った光子結晶で観察される.
結論:
- 負のプアソンの比率の振る舞いは実験的に検証され,幅広い意味を持つ.
- 補助的性質は,恒星の内部と核反応を理解するために重要である.
- 調節可能な巨大なポアソンの比率は,新しい光子結晶装置の可能性を秘めています.
関連する概念動画
Atomic Nuclei: Nuclear Spin State Population Distribution
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.
Electromagnetic Waves in Matter
Electromagnetic waves can travel in the vacuum as well as in matter. For example light, which is an electromagnetic wave, can travel through air, water, or glass.
Consider the electromagnetic wave passing through a dielectric medium. In such a case, Maxwell's equations get modified. In Ampere's law, ε0 , the dielectric permittivity of free space is replaced with ε, the permittivity of dielectric. Also, the vacuum permeability μ0 is replaced by the permeability of the medium, μ.
Furthermore, the...
Consider the electromagnetic wave passing through a dielectric medium. In such a case, Maxwell's equations get modified. In Ampere's law, ε0 , the dielectric permittivity of free space is replaced with ε, the permittivity of dielectric. Also, the vacuum permeability μ0 is replaced by the permeability of the medium, μ.
Furthermore, the...
Effective Value of a Periodic Waveform
The concept of effective value, the root mean square (RMS) value, is crucial in understanding electrical circuits and power delivery. This idea emerges from the necessity to measure the effectiveness of a voltage or current source in supplying power to a resistive load.
The effective value of a periodic current represents the direct current (DC) that conveys the same average power to a resistor as the periodic current itself. This concept is crucial when assessing AC circuits. To determine the...
The effective value of a periodic current represents the direct current (DC) that conveys the same average power to a resistor as the periodic current itself. This concept is crucial when assessing AC circuits. To determine the...
Transfer function and Bode Plots-II
In the standard form, the transfer function is shown in constant gain, poles/zeros at origin, simple poles/zeros, and quadratic poles/zeros; each contributing uniquely to the system's overall response. The term represents the magnitude of the simple zero:
Poisson's Ratio
Poisson's ratio is a material property that indicates their stress response. It explains the connection between the elongation or compression a material undergoes in the direction of an applied force and the contraction or expansion it experiences perpendicular to that force. When a slender bar is loaded axially, it stretches in the direction of the force and contracts laterally. Poisson's ratio is the negative ratio of this lateral contraction to the axial elongation. The negative sign ensures...
Bessel Function of Order Zero
A common physical example of wave propagation with radial symmetry is the ripple formed when a stone is dropped into a still pond. The disturbance originates at a central point and travels outward as a circular wave. As the radius of the wavefront increases, the same initial energy is distributed along a progressively larger circumference. Consequently, the amplitude, or height, of the wave decreases with distance from the center. This decay behavior cannot be captured by simple sine or cosine...


