Clarification of mechanism of superconductivity (in press)ure-induced superconductor,Cs_3C<60>

(压力)诱导超导体Cs_3C<60>超导机理的阐明

• 批准号: 12640557
• 负责人: KUBOZONO Yoshihiro
• 金额: $ 2.3万
• 依托单位: Okazaki National Research Institutes (2001)Okayama University (2000)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640557/
• 关键词: pressure-induced superconductor; structure; x-ray diffraction; high pressure; transport property; electonic property; electron-electron coupling; phase transition; 電子-格子結合; 圧力誘起超伝導

Structures and physical properties of Cs_3C_60 were studied in a pressure region from 1 bar to 6 GPa in order to clarify the mechanism of superconductivity in a pressure-induced superconductor Cs_3C_60. Two phases of body-centered orthorhombic (Immm) and simple cubic (A15 : P<m3>^^^-n) phases exist in Cs_3C_60 at 1bar. Further, we tried to prepare the intermediate phases of Cs_3C_60 and Cs_4C_60 because the Cs atom takes a fractional occupancy of 0.75 in Cs_3C_60, and their structures and physical properties were studied. Only an A15 phase was observed in Cs_<3.00(6)>C_60 and Cs_<35(1)>C60 above 30 kbar. We have also succeeded in preparing the sample of Cs_3C_60 containing 50 % of A15 phase. The Pauli paramagnetic susceptibility was observed in the ESR of Cs_<3.00(6)>C_60 and the intermediate phase Cs_<3.3(1)>C_60. However, the plots of ΔH_pp/(Δg)^2 vs T did not follow the Elliot-Yafet relationship, and the plots of resistivity, p, vs T did not show a normal metallic behavior. The plot … More s suggest a hopping or a fluctuation-induced tunneling conductivity. The AC susceptibilities of the intermediate phases showed no superconducting transition above 1.5 K below 1 0 kbar. This fact suggests that the intermediate phase is not a pressure-induced superconductor. The structures and physical properties of 2D polymeric phase of Na_4C_60 and metallofullerenes were studied in a wide temperature and pressure range in order to search the pressure-induced superconducting phase other than Cs_3C_60. The ESR suggests a metallic behavior for Na_4C_60, while the plots of p vs T shows a semi conducting behavior with a gap energy, E_g, of 0.5 - 0.8 eV. It has been found that the 2D polymeric structure tends to change to a 3D polymeric structure. The structural phase transition was observed from a simple cubic (P03) to a face-centered cubic phase in Dy@C_82 isomer I around 310 K. The plots of p vs T show a semi conducting behavior with a small E of 0.2 eV. This suggests an appearance of novel physical properties such as semiconductor-metal transition and superconductivity under high pressure. Less

在压力区域从1 bar到6 GPA进行了CS_3C_60的结构和物理特性，以阐明在压力诱导的超导体CS_3C_60中超导性的机理。以人体为中心的矫正骨（IMMM）和简单的立方体（A15：P <m3> ^^ - n）阶段的两个阶段存在于1BAR的CS_3C_60中。此外，我们试图准备CS_3C_60和CS_4C_60的中间阶段，因为CS原子在CS_3C_60中的分数占用率为0.75，并且研究了它们的结构和物理特性。在CS_ <3.00（6）> C_60和CS_ <35（1）> C60中，仅观察到A15相。我们还成功地准备了包含A15期50％的CS_3C_60样本。在CS_ <3.00（6）> C_60的ESR和中间相CS_ <3.3（1）> C_60中观察到Pauli parmagnetic敏感性。但是，ΔH_pp/（ΔG）^2 vs t的图没有遵循Elliot-yFet关系，并且抗性，P，Vs vs T的图没有显示出正常的金属行为。该地块……更多的S提示跳跃或波动引起的隧道电导率。中间相的AC敏感性显示出低于1 0 kbar以下1.5 k的超导过渡。这一事实表明，Na_4C_60的2D聚合物相和金属氟烯的结构和物理特性在较宽的温度和压力范围内进行了研究，以搜索除CS_3C_60以外的压力诱导的超导相。 ESR提出了Na_4C_60的金属行为，而Ps vs v的图显示了一个半传导行为，其间隙能E_G为0.5-0.8 eV。已经发现2D聚合物结构倾向于变为3D聚合物结构。从简单的立方体（P03）到Dy@C_82异构体I左右，在310 K左右观察到了结构相变。Pvs vs t的图显示了一个半传导行为，其小E的小E为0.2 eV。这表明在高压下出现了新型物理特性，例如半导体金属过渡和超导性。较少的

项目成果

高林康裕, 久保園芳博 他7名: "Pressure and temperature dependencics of the structural properties of Dy@C_<82> isomer I"Physical Review B. 65. 73405-1-73405-4 (2002)

Yasuhiro Takabayashi、Yoshihiro Kubozono 等 7 人：“Dy@C_<82> 异构体 I 结构特性的压力和温度依赖性”物理评论 B. 65. 73405-1-73405-4 (2002)

藤木聡,久保園芳博 他10名: "Structure and scattering of Cs_3C_<60> under high pressure"Physical Review B. 62. 5366-5369 (2000)

Satoshi Fujiki、Yoshihiro Kubozono 等 10 人：“高压下 Cs_3C_<60> 的结构和散射”Physical Review B. 62. 5366-5369 (2000)

久保園芳博: "赤阪健, 永瀬茂編A New Family of Carbon Clustersの12章を担当:Encapsulation of atom into C_<60> cage"Kluwer Academic Publishers b.v.(印刷中). (2002)

Yoshihiro Kubozono：“Ken Akasaka 和 Shigeru Nagase 编辑的碳簇新家族第 12 章：将原子封装到 C_<60> 笼中”Kluwer 学术出版社 b.v.（出版中）。

T. Kanbara, Y. Kubozono, Y. Takabayashi, S, Fujiki, S. Iida, Y. Haruyama, S. Kashino, S. Emura and T. Akasaka: "Dy@C_60: evidence for endohedral structure and electron transfer"Phys. Rev. B. 64. 113403-1-113403-3 (2001)

T. Kanbara、Y. Kubozono、Y. Takabayashi、S、Fujiki、S. Iida、Y. Haruyama、S. Kashino、S. Emura 和 T. Akasaka：“Dy@C_60：内面结构和电子转移的证据”Phys

久保園芳博: "赤阪健, 永瀬茂編 A New Family of Carbon Clusterの12章を担当:Encupslation of atom into C_<60> cage"Kluwer Academic Publishers b.v.. (2002)

Yoshihiro Kubozono：“Ken Akasaka 和 Shigeru Nagase 编辑的碳簇新家族第 12 章：将原子封装到 C_<60> 笼中”Kluwer 学术出版社 b.v.（2002 年）