超低温磁気冷却 無機材料:設計合成からアディアバティック解磁気冷却まで
Qiao-Fei Xu1, Ruo-Tong Wu1, La-Sheng Long1
1Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Accounts of chemical research
|August 29, 2025
まとめ
研究者は,高磁気エントロピー変化 (-ΔSm) と低オーダー温度 (T0) を達成するアディアバティック脱磁冷却 (ADR) のための新しい磁気冷媒を開発した. これらの新しい材料は,量子コンピューティングと天文学のために1ケルビン未満のヘリウムフリー冷却を大幅に進めている.
科学分野:
- 材料科学
- 低温物理学
- 量子技術
背景:
- アディアバティック脱磁冷却 (ADR) は,ケルビン以下冷却のための唯一のヘリウムフリー技術です.
- 量子コンピューティングと天文学における需要の増加は,高度なADRシステムを必要としています.
- 既存の磁気冷媒は,磁気エントロピーの変化 (-ΔSm) とオーダー温度 (T0) の間のトレードオフに直面しています.
研究 の 目的:
- ADRのための次の世代の磁気冷媒を合理的に設計する.
- 高ΔSmと低T0を同時に達成するという課題を克服する.
- ミリケルビン温度でのADR性能を向上させるため
主な方法:
- 調節磁気パラメータ:オーダー温度 (T0),交換,および二極相互作用.
- フロイドブリッジを反鉄磁気フレームワークに組み込む.
- 平均場近似と量子モンテカルロ (QMC) シミュレーションを用いて.
- Gd(OH) F2,LiGd0.1Yb0.9F4,KYb3F10などの新材料を合成して試験する.
主要な成果:
- フッ素の組み込みは,反鉄磁性を弱鉄磁性へとシフトさせ,T0を下げ,−ΔSmを増加させた.
- Gd(OH) F2は,弱い磁気相互作用と高い磁気密度をバランスすることによって記録 -ΔSm値を達成しました.
- LiGd0.1Yb0.9F4は,商用冷媒の2倍の冷却能力で160mKまで冷却されます.
- KYb3F10は27.2mKに達し,次世代のADR冷媒として有望であることを示しました.
結論:
- 合理的な設計戦略は,磁気冷媒における -ΔSmを向上させ,T0を抑制することに成功した.
- 競争する磁気相互作用と 化学的乱れをバランスさせることが 高性能の鍵です
- 開発された冷媒は,基本的な低温システムと応用された低温システムにおけるADR技術の進歩のための堅固な経路を提供します.
関連する概念動画
Types Of Superconductors
1.1K
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...
1.1K
Ferromagnetism
2.5K
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...
2.5K
Superconductor
1.2K
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...
1.2K
Eddy Currents
1.7K
Since eddy currents occur only in conductors, magnets can separate metals from other materials. For example, in a recycling center, trash is dumped in batches down a ramp, beneath which lies a powerful magnet. Conductors in the trash are slowed by eddy currents, while nonmetals in the trash move on, separating from the metals. This works for all metals, not just ferromagnetic ones.
Other major applications of eddy currents appear in metal detectors and the braking systems of trains and roller...
Other major applications of eddy currents appear in metal detectors and the braking systems of trains and roller...
1.7K
Refrigerators and Heat Pumps
2.4K
Refrigerators or heat pumps are heat engines operating in a reverse direction. For a refrigerator, the focus is on removing heat from a specific area, whereas, for a heat pump, the focus is on dumping heat into one particular area. A refrigerator (or heat pump) absorbs heat Qc from the cold reservoir at Kelvin temperature Tc and discards heat Qh to the hot reservoir at Kelvin temperature Th, while work W is done on the engine’s working substance.
A household refrigerator removes heat from...
A household refrigerator removes heat from...
2.4K
Magnetic Susceptibility and Permeability
1.4K
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...
1.4K


