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约瑟夫森结的超晶格，即沿晶体学c轴的无限阵列的约瑟夫森结。这产生了出现在太赫兹频率区域的集体激发模式，即所谓的约瑟夫森等离子体模式。然而，约瑟夫森等离子体模式是纵向激发，并且不直接与太赫兹辐射耦合。为了产生光活性等离子体模式，约瑟夫森耦合强度的空间调制是必要的。在本项目中，我们通过调制约瑟夫森耦合强度成功地操纵了光学约瑟夫森等离子体模式：(1)使用化学/结构操作合成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，从而形成具有不同耦合强度的约瑟夫森结的交替阵列，以及(2)平行施加外部磁场 到CuO_2平面，其作为约瑟夫森涡旋渗透到CuO_2平面之间，从而调节约瑟夫森耦合强度。

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.