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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

基本信息

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

项目摘要

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

在与强电子-电子相关的磁有序的邻接处经常发现非常规的超导性。我们知道，正态具有强的各向异性和强的电子-电子相关性，这在高t的铜酸盐中具有代表性。为了了解这些特性在正常状态下对超导性的影响，我们在氧化物超导体中进行了压力实验。(1)压力诱导铁磁性的可能性SrィイD22摊位ィエD2RuOィイD24ィエD2As压力,从而控制电子的相关适用技术发现磁大州SrィイD22摊位ィエD2RuOィイD24ィエD2系统。我们测量了Sr φ φ D22 φ φ D2RuO φ φ D24 φ φ D2中电阻率的温度和压力依赖性。在1.5 ~ 5gpa范围内，面内电阻率的温度依赖性在40K左右存在压力诱发峰。在超过5GPa的压力下，抑制了峰后，电阻率呈现出T γ γ γ /3 γ γ γ γ的依赖性。这些行为强烈表明一种压力诱导铁磁性。(2)角色的二维电子态超导在洛杉矶ィイD22-xィエD2SrィイD2xィエD2CuOィイD24ィエD2Strong two-dimensionality,这是在c-axis电阻率的奇异行为表达之后,氧化物超导体的关键人物,虽然低维数通常被称为传统的超导的破坏性因素。为了探讨电子态的二维性是如何在T′′′D2c′′rd2中反映出来的，我们测量了各向异性压力下La′r22′x′r2sr′r2x′r2cuo′r24′r24u′rd2的c轴电阻率。c轴压缩降低了c轴电阻率，显著降低了c轴电阻率，而c轴延伸则提高了c轴电阻率，使c轴电阻率从38K提高到51 k。6K, 8GPa。我们发现T的变化ィイD2cィエD2尺度c-axis电阻率的函数,并且c-axis压力系数远远强于ab-axis,这些暗示TィイD2cィエD2主要取决于层间,而不是平面,晶格参数。少