YBa2Cu3O6.5における強化された超伝導性の基礎として非線形格子ダイナミクス
R Mankowsky1, A Subedi2, M Först3
11] Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany [2] University of Hamburg, 22761 Hamburg, Germany [3] Center for Free-Electron Laser Science (CFEL), 22761 Hamburg, Germany.
Nature
|December 5, 2014
まとめ
テラヘルツパルスは,YBa2Cu3O6+xの結晶構造を変形することによって,一時的な超伝導性を誘導します. 52ケルビン以上で観測されるこの非均衡状態は,電子構造の有意な変化を示し,超伝導性を好む.
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
- 固体化学 固体化学
背景:
- テラヘルツ周波数の光学パルスは,固体内の振動モードを共振的に刺激し,構造的変形を引き起こします.
- 複合酸化物では,この刺激が,絶縁体から金属への移行や超伝導性などの移行を誘発することが示されています.
- 室温までの一時的な超伝導性は,YBa2Cu3O6+x.で観察されています.
研究 の 目的:
- YBa2Cu3O6+x.におけるエキゾチックな非均衡状態の結晶構造を決定する.
- テラヘルツ刺激によって誘発される格子ダイナミクスと電子構造の変化を理解するために.
- この材料における一時的な超伝導性の背後にあるメカニズムを解明する.
主な方法:
- 5秒間のX線 difraktionを用いて,結晶構造を調査した.
- 電子構造を分析するために,初期密度関数理論 (DFT) の計算が採用されました.
- 非線形格子刺激は,テラヘルツ周波数の光学パルスを使用して適用されました.
主要な成果:
- 52 ケルビン以上の非線形格子刺激は,Cu-O2 結合距離の同時変化を引き起こしました (イントラバイヤー増加,インターバイヤー減少).
- 平面内O-Cu-O結合の歪みにおけるアニゾトロプ的変化が観察されました.
- DFTの計算は,電子構造の劇的な変更を明らかにし,機内電子特性を強化しました.
結論:
- 観察された構造の変化は,エキゾチックな非均衡状態と関連しています.
- 強化された平面内電子構造の特徴は,超伝導性を好む重要な要因である.
- この研究は,複雑な酸化物における光誘導の超伝導性メカニズムについての洞察を提供します.
さらに関連する動画
06:49Radio Frequency Magnetron Sputtering of GdBa2Cu3O7âˆ'ÃŽ ´/ La0.67Sr0.33MnO3 Quasi-bilayer Films on SrTiO3 STO Single-crystal Substrates
Published on: April 12, 2019
8.2K
05:39Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform
Published on: August 2, 2019
10.5K
関連する概念動画
02:54Trends in Lattice Energy: Ion Size and Charge
27.8K
An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure of the strength of this attraction. The lattice energy (ΔHlattice) of an ionic compound is defined as the energy required to separate one mole of the solid into its component gaseous ions. For the ionic solid sodium chloride, the lattice energy is the enthalpy change of the process:
27.8K
01:24Superconductor
2.1K
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...
2.1K
01:28Types Of Superconductors
1.9K
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...
1.9K
01:31Ferromagnetism
3.6K
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...
3.6K
01:17Theory of Metallic Conduction
2.0K
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,...
2.0K
02:33Lattice Centering and Coordination Number
16.4K
The structure of a crystalline solid, whether a metal or not, is best described by considering its simplest repeating unit, which is referred to as its unit cell. The unit cell consists of lattice points that represent the locations of atoms or ions. The entire structure then consists of this unit cell repeating in three dimensions. The three different types of unit cells present in the cubic lattice are illustrated in Figure 1.
Types of Unit Cells
Imagine taking a large number of identical...
Types of Unit Cells
Imagine taking a large number of identical...
16.4K