Search for Novel Superconductors with High-Tc in the Ru Oxide System and Possibility for Coexistence of Magnetism and Superconductivity

寻找Ru氧化物体系中的新型高温超导体以及磁性与超导共存的可能性

• 批准号: 12440195
• 负责人: YOSHIMURA Kazuyoshi
• 金额: $ 9.73万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12440195/
• 关键词: Ru Oxide; 4d-5d electron system; Oxide Superconductor; Metal-Insulator Transition; Strong Electron Correlation; Low Dimensional Magnetism; Perovskite; Pyrochlore; 層状ペロブスカイト; 4d・5d遷移金属酸化物; 磁性と超伝導; クーパー対の対称性; 高温超伝導; 核磁気共鳴・緩和; 4d遷移金属; p波超伝導

It is quite important to find out new compounds which show new physical properties, leading to a possible breakthrough in the field of solid state sciences. In this context, the role of chemists is very important in this research field.We have investigated the syntheses and chemical and physical properties of various 4d and 5d transition metal oxide systems, and tried to find new and novel compounds which show new-type of quantum phenomena, especially, superconducting and metal-insulator transition compounds.As a result, recently, the Pyrochlore oxide Cd_2Re_2O_7 has been found to exhibit superconductivity at about 1 K, which is a firstly-found superconductor in the frustrated-spin system. We also found a pseudo-gap behavior in Cd_2Re_2O_7 below T^* of about 200K which resembles the spin-gap behavior in the cuprate high-T_c systems.We have also found new-type compounds with interesting physical and chemical properties in this research program as follows: EuSr_2RuCu_2O_8 (coexistence of ferromagnetism and superconductivity), Tl_2Ru_2O_7 (Metal-Insulator transition and spin-gap behavior below T_<M-1>), Bi_2Ru_2O_7 and Pb_2Ru_2O_7 (Pauli paramagnetism with antiferromagnetic spin fluctuations). Now, further study of physical properties of these compounds including spin dynamics is still in progress in detail, and will be reported elsewhere.

寻找具有新物理性质的新化合物非常重要，从而可能在固态科学领域取得突破。在此背景下，化学家在这一研究领域中的作用非常重要。我们研究了各种4d和5d过渡金属氧化物体系的合成以及化学和物理性质，并试图寻找表现出新型性质的新型化合物。近年来，人们首次发现烧绿石氧化物Cd_2Re_2O_7在1K左右表现出超导性。受挫自旋系统中的超导体。我们还在 Cd_2Re_2O_7 中发现了约 200K T^* 以下的赝能隙行为，这类似于铜酸盐高 T_c 系统中的自旋能隙行为。在本研究项目中我们还发现了具有有趣的物理和化学性质的新型化合物如下：EuSr_2RuCu_2O_8（铁磁性和超导性共存）、Tl_2Ru_2O_7（金属-绝缘体）低于 T_<M-1> 的跃迁和自旋能隙行为）、Bi_2Ru_2O_7 和 Pb_2Ru_2O_7（具有反铁磁自旋涨落的泡利顺磁性）。现在，对这些化合物的物理性质（包括自旋动力学）的进一步详细研究仍在进行中，并将在别处报道。

项目成果

H.Sakurai: "Antiferromagnetic Order in Bi_4Cu_3V_2O_<14> with Novel Spin Chain"J. Phys. Soc. Jpn.. 71. 1161-1165 (2002)

H.Sakurai：“具有新型自旋链的 Bi_4Cu_3V_2O_<14> 中的反铁磁顺序”J。

H. Sakai, H. Ohno, K. Yoshimura, H. Kato, S. Kambe, R. E. Walstedt, T. D. Matsuda, Y. Haga, S. Ikeda and Y. Onuki: "Superconductivity in pyrochlore oxide Cd_2Re_2O_7"Physica C. 378-381. 43-46 (2002)

H. Sakai、H. Ohno、K. Yoshimura、H. Kato、S. Kambe、R. E. Walstedt、T. D. Matsuda、Y. Haga、S. Ikeda 和 Y. Onuki：“烧绿石氧化物 Cd_2Re_2O_7 中的超导性”Physica C. 378-

T.Yokoyama: "Cu NQR study of Hole Doped 1-D Cu Chain Oxide Ca_<0.85>CuO_2"J. Phys. Chem. Solids. 63. 1111-1114 (2002)

T.Yokoyama：“空穴掺杂一维铜链氧化物Ca_<0.85>CuO_2的Cu NQR研究”J。

T. Waki, H. Kato, M. Kato and K. Yoshimura: "^<51>V NMR Study of the V Hollandite system, Bi_xV_8O_<16>: spin-singlet formation below M-I transition"J. Phys. Soc, Jpn.. 71. 160-162 (2002)

T. Waki、H. Kato、M. Kato 和 K. Yoshimura：“V Hollandite 体系的^ 51 V NMR 研究，Bi_xV_8O_<16>：M-I 跃迁以下的自旋单线态形成”J。

S.Niitaka: "High-Field Magnetization and Neutron Diffraction Studies of One-Dimensional Compound Ca_3CoRhO_6"J.Phys.Soc.Jpn.. 70(5). 1222-1225 (2001)

S.Niitaka：“一维化合物Ca_3CoRhO_6的高场磁化和中子衍射研究”J.Phys.Soc.Jpn.. 70(5)。