Search and Control of Josephson Plasma Modes in 7^* Type High-Tc Superconductors

7^*型高温超导体约瑟夫森等离子体模式的搜索与控制

• 批准号: 13450007
• 负责人: UCHIDA Shin-ichi
• 金额: $ 7.94万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13450007/
• 关键词: 7^* Cuprate; High-T_c superconductivity; Optical Josephson-Plasma Mode; Josephson Superlattice; Josephson Vortex; THz Spectrum; ストライプ秩序; テラヘルツ励起モード

The structure of high-T_c copper oxide superconductors is a superlattice of Josephson junctions, an infinite array of Josephson junctions along the crystallographic c- axis. This gives rise to a collective excitation mode, so-called Josephson plasma mode, appearing in the THz frequency region. Hoever, the Josephson plasma mode is a longitudinal excitation, and does not directly couple with THz radiation. In order to produce optical-active plasma mode, spatial modulation of the Josephson coupling strength is necessary. In the present project, we successfully manipulated the optical Josephson plasma mode by modulating the Josephson coupling strength(1) using chemical/structural operation to synthesize T^* type high-T_c cuprates which have apical oxygen atoms on one side of an CuO_2 plane and hence form an alternating array of Josephson junctions with different coupling strengths, and(2) applying external magnetic field parallel to the CuO_2 planes which penetrate as Josephson vortices between the CuO_2 planes and thus modulate the Josephson coupling strength.

高t_c氧化铜超导体的结构是一个约瑟夫森结的超晶格，一个沿晶体学c轴的无限约瑟夫森结阵列。这就产生了一个集体激发模式，即所谓的约瑟夫森等离子体模式，出现在太赫兹频率区域。然而，约瑟夫森等离子体模式是纵向激励，不直接耦合太赫兹辐射。为了产生光主动等离子体模式，需要对约瑟夫森耦合强度进行空间调制。在本项目中，我们成功地利用化学/结构操作通过调制Josephson耦合强度(1)来操纵光学Josephson等离子体模式，合成了T^*型高t_c铜酸盐，该铜酸盐在CuO_2平面的一侧具有顶端氧原子，从而形成了具有不同耦合强度的Josephson结的交替阵列。(2)施加平行于CuO_2平面的外磁场，在CuO_2平面之间形成Josephson涡，从而调节Josephson耦合强度。

项目成果

A.Lanzara: "Evidence for ubiquitous strong electron-phonon coupling in high-temperature superconductors"Nature. 412. 510-514 (2001)

A.Lanzara：“高温超导体中普遍存在强电子声子耦合的证据”自然。

T. Kakeshita: "Transverse Josephson Plasma Mode in T^* Cuprate Superconductors"Phys. Rev. Lett.. 86. 4140-4143 (2001)

T. Kakeshita：“T^* 铜酸盐超导体中的横向约瑟夫森等离子体模式”Phys。

B.Nachumi: "Raman scattering in striped La_<1.475>Nd_<0.4>Sr_<0.125>CuO_4"Phys. Rev. B. 65. 092504 (2002)

B.Nachumi：“条纹 La_<1.475>Nd_<0.4>Sr_<0.125>CuO_4 中的拉曼散射”Phys。

S. Arumugam: "Competition of Static Stripe and Superconducting Phases in La_<L48>Nd_<0.4>Sr_<0.12>CuO_4 Controlled by Pressure"Phys. Rev. Lett.. 88. 247001 (2002)

S. Arumugam：“压力控制下 La_<L48>Nd_<0.4>Sr_<0.12>CuO_4 中静态条纹与超导相的竞争”Phys。

Yayu Wang: "High Field Phase Diagram of Cuprate Derived from the Nernst Effect"Phys. Rev. Lett.. 88. 257003 (2002)

王亚宇：“能斯特效应衍生的铜酸盐高场相图”Phys.