Pressure effect on the 2D-electronic state and the superconductivity in oxide superconductors

压力对氧化物超导体中二维电子态和超导性的影响

• 批准号: 10640349
• 负责人: NAKAMURA Fumihiko
• 金额: $ 1.86万
• 依托单位: Hiroshima University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640349/
• 关键词: strongly correlated electron system; oxide superconductor; pressure effect; low dimensionality; transport properties

Unconventional superconductivity is frequently found at adjacencies of the magnetic ordering related to strong electron-electron correlation. It is known that the normal state is characterized by strong anisotropy and strong electron-electron correlation, as is representatively seen in high-TィイD2cィエD2 cuprates. To understand the effect of these characters in normal state on the superconductivity, we perform pressure experiments in oxide superconductors.(1) Possibility of pressure induced ferromagnetism in SrィイD22ィエD2RuOィイD24ィエD2As is known pressure, which can control the electron-electron correlation is suitable technique to discover the magnetic grand state in SrィイD22ィエD2RuOィイD24ィエD2 system. We measure temperature and pressure dependence of resistivity in SrィイD22ィエD2RuOィイD24ィエD2. A pressure induce hump at around 40K is found in the temperature dependence of in-plane resistivity under 1.5-5GPa. Moreover, the resistivity shows TィイD14/3ィエD1 -dependence after suppressing the hump under pr … More essure over than 5GPa. These behaviors strongly indicate a pressure-induced ferromagnetism.(2) Role of two-dimensional electronic state in superconductivity in LaィイD22-xィエD2SrィイD2xィエD2CuOィイD24ィエD2Strong two-dimensionality, which is after expressed in exotic behavior of the c-axis resistivity, is a key character of oxide superconductors, though low dimensionality is generally known as a destructive factor for conventional superconductivity. To explore how the two-dimensionality in the electronic state is reflected in TィイD2cィエD2, we have measured the c-axis resistivity for LaィイD22-xィエD2SrィイD2xィエD2CuOィイD24ィエD2 under anisotropic pressure. The c-axis compression, which decreases the c-axis resistivity, reduces TィイD2cィエD2 drastically, whereas c-axis extension, which increases the c-axis resistivity, enhances TィイD2cィエD2 from 38K at ambient pressure to 51 .6K at 8GPa. We find that the variation of TィイD2cィエD2 scales as a function of the c-axis resistivity, and that the c-axis pressure coefficient is much stronger than the ab-axis one, These imply that TィイD2cィエD2 depends primarily on the interlayer, rather than the in-plane, lattice parameter. Less

非常规超导电性经常出现在与强电子-电子关联相关的磁序的邻接位置。众所周知，正常态的特征是强各向异性和强电子-电子关联，这在高T-ィイD2CィエD2铜酸盐中是有代表性的。为了了解正常状态下的这些特性对超导电性的影响，我们在氧化物超导体中进行了压力实验：(1)已知的压致铁磁性存在于SrィイD22ィエD2RuOィイD24ィエD2As中，可以控制电子-电子关联的压强是发现SrィイD22ィエD2RuOィイD24ィエD2系统中磁性宏态的合适技术。我们测量了SrィイD22ィエD2RuOィイD24ィエD2的电阻率随温度和压力的变化关系。在1.5-5 GPa面内电阻率随温度变化的曲线中，发现在40K附近有一个压力感应峰。此外，在Prィイ下抑制驼峰后，电阻率表现出TィエD14/3…依赖关系压力超过5 Gpa。这些行为强烈地表明了压致铁磁性。(2)二维电子态在LaィイD22-xィエD2SrィイD2XィエD2CuOィイD24ィエD2中的超导性中的作用强的二维性在c轴电阻率的奇异行为中表现出来，这是氧化物超导体的一个关键特征，尽管低维通常被认为是传统超导电性的破坏因素。为了探索在TィイD2CィエD2中如何反映电子态的二维性，我们测量了LaィイD22-xィエD2SrィイD2XィエD2CuOィイD24ィエD2在各向异性压力下的c轴电阻率。C轴压缩降低了c轴的电阻率，显著降低了TィイD2CィエD2，而c轴的延伸增加了c轴的电阻率，将TィイD2CィエD2从常压下的38K提高到8 GPa时的51.6K。我们发现TィイD2CィエD2的变化是c轴电阻率的函数，c轴的压力系数远大于ab轴的压力系数，这意味着TィイD2CィエD2主要依赖于层间而不是面内的晶格参数。较少

项目成果

F. Nakamura, et al.: "Role of two-dimensional electronic state in superconductivity in LaィイD22-xィエD2SrィイD2xィエD2CuOィイD24ィエD2"Physical Review B. 61. 107-110 (2000)

F. Nakamura 等人：“LaD22-xD2SrD2xD2CuOD24D2 中二维电子态在超导中的作用”物理评论 B. 61. 107-110 (2000)

K.Yoshida et al.: "Electronic crossover in the highly anisotropic normal state of Sr_2 RuO_4 from pressure effect on electrical resistivity" Physical Review B. 58. 15062-15066 (1998)

K.Yoshida 等人：“来自压力对电阻率影响的 Sr_2 RuO_4 高度各向异性正常状态下的电子交叉”物理评论 B. 58. 15062-15066 (1998)

F.Nakamura et al.: "Tc enhancement in La_<2-x>Sr_xCuO_4 under anisotropic pressure"J.Low Temperature Physics. 117. 1145-1149 (1999)

F.Nakamura等：“各向异性压力下La_2-xSr_xCuO_4的Tc增强”J.低温物理学。

S.Sakita et al.: "Structural Transitions and Localization in La_<2-x>Sr_xCuO_4 with P〜1/8"J.Phys.Soc.Jpn.. 68. 2755-2761 (1999)

S. Sakita 等人：“La_2-xSr_xCuO_4 中 P~1/8 的结构转变和定位”J.Phys.Soc.Jpn.. 68. 2755-2761 (1999)

F.Nakamura et al.: "Transport Properties of La_<2-x>Sr_xCuO_4 under Pressure"Physica C. 317-318. 358-364 (1999)

F.Nakamura等人：“La_2-x>Sr_xCuO_4在压力下的传输特性”Physica C.317-318。