クプラート超伝導体における擬似ギャップの基本状態
T Valla1, A V Fedorov, Jinho Lee
1Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA. valla@bnl.gov
Science (New York, N.Y.)
|November 18, 2006
まとめ
La(2-x) BaxCuO4 の超伝導性は,スピン・チャージ・オーダーによって抑制されます. 超伝導性がなくても,エネルギーギャップは存在し,相相不一致のd波状態を示唆し,クーパーペアで秩序ある構造を形成します.
科学分野:
- 凝縮物質物理学 凝縮物質物理学
- 材料科学 材料科学とは
- 超伝導性は超伝導性である.
背景:
- La(2-x) BaxCuO4はドーピングレベルに敏感な超伝導性を示しています.
- "ストライプ"として知られる静的なスピンと電荷の順序は,x = 1/8の近くに現れ,超伝導性を抑制します.
研究 の 目的:
- x = 1/8のドーピングレベルでのLa(2-x) BaxCuO4の電子構造を調べる.
- 超伝導性がストライプ形成によって抑制されたときの電子状態の性質を決定する.
主な方法:
- 角度解像度光放射スペクトロスコーピー (ARPES) とは,角度解像度光放射スペクトロスコーピー (ARPES) とは,角度解像度光放射スペクトロスコーピー (ARPES) とは
- スキャントンネル顕微鏡 (STM)
主要な成果:
- フェルミ表面でエネルギーギャップが検出されました.
- ギャップの大きさと状態の線形密度は,d波対称性と一致しています.
- このギャップは,x = 1/8で超伝導性が消滅しても,ノードが4点にある場合でも存在します.
結論:
- x = 1/8 の非超伝導状態は,相不一致の d 波超伝導体である.
- この状態のクーパー・ペアは,超伝導性を達成するのではなく,スピン・チャージ・オーダーされた構造を形成する.
関連する概念動画
01:24Superconductor
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...
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...
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...
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.
01:17Theory of Metallic Conduction
The conduction of free electrons inside a conductor is best described by quantum mechanics. However, a classical model makes predictions close to the results of quantum mechanics. It is called the theory of metallic conduction.
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...
01:28Debye–Huckel–Onsager Conductance Equation
The Debye-Hückel-Onsager equation is a cornerstone of physical chemistry, providing a method to determine the molar conductance (Λm) and molar conductance at infinite dilution (Λ°m) for uni-univalent electrolytes.Uni-univalent electrolytes are electrolytes that dissociate in solution to produce one cation with a +1 charge and one anion with a –1 charge per formula unit.This equation addresses two crucial phenomena: the asymmetry effect and the electrophoretic effect. According to this equation,...