スピンの超固体候補Na2BaCo(PO4) 2における巨大な磁熱効果
Junsen Xiang1, Chuandi Zhang2, Yuan Gao2,3
1Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
Nature
|January 10, 2024
まとめ
研究者らは,Na2BaCo ((PO4) 2) で超固体の量子磁性アナログであるスピン超固体を発見した. この発見は ケルビン未満の冷却の可能性があり このエキゾチックな量子状態を実現する上で 以前の課題を克服しました
科学分野:
- 凝縮物質物理学
- 量子磁気について
- 量子材料について
背景:
- 超固体とは 固体と超流体の両方の性質を示す 物質のエキゾチックな量子状態です
- 凝縮された物質のシステムにおける 超固体性を実現することは 長い間 課題でした
- 4Heのような超固体の以前の報告は後に人工物として特定されました.
研究 の 目的:
- 凝縮された物質の 超固体の 量子磁性 アナログの証拠を見つけるために
- この新しい量子状態の性質と 潜在的応用を調査する
主な方法:
- 三角格子反鉄磁石Na2BaCo(PO4) 2の合成
- デマグネティゼーション冷却中の巨大な磁熱効果の実験観察.
- 簡単な軸のハイゼンベルグモデルを用いた理論的シミュレーション
- スピンの順序と層間の不相応性を特定する中性子 difraktion.
主要な成果:
- Na2BaCo ((PO4) 2) のスピン超固体相の証拠が見つかりました.
- 100mK未満の巨大な磁熱効果が観察されました.
- 実験上の重要なフィールドと冷却プロファイルは,理論的なシミュレーションと一致しています.
- 中性子 difraktionは3つのサブレットのスピン固体の順序と層間の不相応性の共存を確認した.
結論:
- この研究は,挫折した量子磁石のスピン超固体相に関連した強いエントロピー効果を明らかにしています.
- この発見は,ヒリウム不足に関する懸念に対処し,サブケルビン冷却技術の有望な道を開きます.
関連する概念動画
01:28Types Of Superconductors
982
A superconductor is a substance that offers zero resistance to the electric current when it drops below a critical temperature. Zero resistance is not the only interesting phenomenon as materials reach their transition temperatures. A second effect is the exclusion of magnetic fields. This is known as the Meissner effect. A light, permanent magnet placed over a superconducting sample will levitate in a stable position above the superconductor. High-speed trains that levitate on strong...
982
03:02Colors and Magnetism
11.7K
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
11.7K
01:30Paramagnetism
2.5K
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...
2.5K
01:31Ferromagnetism
2.4K
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...
2.4K
01:24Superconductor
1.1K
A substance that reaches superconductivity, a state in which magnetic fields cannot penetrate, and there is no electrical resistance, is referred to as a superconductor. In 1911, Heike Kamerlingh Onnes of Leiden University, a Dutch physicist, observed a relation between the temperature and the resistance of the element mercury. The mercury sample was then cooled in liquid helium to study the linear dependence of resistance on temperature. It was observed that, as the temperature decreased, the...
1.1K
01:26Diamagnetism
2.4K
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....
2.4K