電子ドーピングされた高温超伝導体Nd2-xCexCuO4+/-デルタにおけるスピン相関
E M Motoyama1, G Yu, I M Vishik
1Department of Physics, Stanford University, Stanford, California 94305, USA.
Nature
|January 12, 2007
まとめ
電子ドーピングされたコプラートにおける高温超伝導性は,遠距離反鉄磁力学と共存しない可能性があります. 代わりに,量子的臨界点は,これらの現象を,スピン相関が擬似ギャップを駆動しているものと結びつけています.
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
- 量子マグネティズム 量子マグネティズムとは
背景:
- 高トランジション温度 (高T ((c)) 超伝導性は,しばしば反鉄磁気相の近くで発生し,磁気刺激がペアリングに役割を果たす可能性があることを示唆しています.
- 二次元の反鉄磁性スピン相関のドーピングと温度依存を理解することは,この関係を明らかにするために不可欠です.
- Nd2-xCexCuO4+/-delta (NCCO) のような電子ドーピングされたコプラートは,反鉄磁性がさらに広がり,超伝導性と重なり合う非対称な相図を示します.
研究 の 目的:
- 電子ドーピングされたコプラートにおける長距離反鉄磁性と超伝導性の共存を調査する.
- 超伝導性の発生時の量子相変化の性質を調査する.
- これらの材料における擬似ギャップ現象の起源を決定する.
主な方法:
- 不弾性磁性中性子散乱の測定は,電子ドーピングされたコプラートで行われた.
- 分析は,反鉄磁性スピン相関のドーピングと温度依存性に焦点を当てました.
- スピン相関と擬似ギャップに関する理論的提案との比較.
主要な成果:
- 証拠によると,真の長距離反鉄磁性と超伝導性は,これらの材料で共存しないことを示唆しています.
- 超伝導性の出現時に磁気量子臨界点が特定され,異様な量子相転換を示唆した.
- 擬似ギャップ現象は,理論的な予測と一致するスピン相関の蓄積と関連しています.
結論:
- この研究は,電子ドーピングされたコプラートにおける長距離反鉄磁気と高T (c) 超伝導性の間の直接的な共存の概念に異議を唱える.
- 量子的臨界点ではなく,共存が,これらの電子相間の移行を統制しているように見える.
- スピン相関は,電子ドーピングされた材料における擬似ギャップの背後にある駆動メカニズムとして特定されています.
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
04:51Comparison of Two Different Synthesis Methods of Single Crystals of Superconducting Uranium Ditelluride
Published on: July 8, 2021
関連する概念動画
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
03:02Colors and Magnetism
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 eye.
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 eye.
01:14Atomic 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.
01:26Diamagnetism
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.
01:28Types Of Superconductors
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...
01:31Ferromagnetism
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...