Electron Self-Organizations and Transport Phenomena in High-Tc Cuprate Superconductors

高温铜酸盐超导体中的电子自组织和输运现象

基本信息

批准号：
16340112
负责人：
ANDO Yoichi
金额：
$ 11.1万
依托单位：
Osaka University (2007)Central Research Institute of Electric Power Industry (2004-2006)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2007
项目状态：
已结题

项目摘要

It is recognized that some sort of electron self-organization occurs in high-Tc cuprate superconductors due to strong electron correlations. Also, it seems likely that in cuprates the electron self-organization phenomena lie behind their peculiar electronic states such as unusual insulating normal state under high magnetic fields or intrinsic inhomogeneity of the superconducting gap. This project has clarified various aspects of the electron self-organization phenomena in cuprates through experiments using high-quality single crystals, in particular their transport properties measurements under extreme conditions. Principal results are the following:1. We discovered the existence of "magic doping fractions" for charge ordering in La_2-X_Sr_xCuO_4, and showed that a checkerboard model consistently explains the observed fractions.2. Extensive measurements of ultra-low-temperature thermal conductivity of YBa_2Cu_3O_y, La_2-x_Sr-xCuO_4, and Bi_2Sr_2CaCu_xO_<8+δ> revealed a breakdown of the "universal thermal conductivity", which is generically expected for d-wave BCS superconductors. This breakdown is apparently related to the peculiar superconducting gap inhomogeneity in cuprates.3. Through the ultra-low-temperature measurements of transport properties of nonsuperconducting YBa_2Cu_3O_y, where a self-organized resistivity anisotropy is known to exist, we elucidated that the electron self-organized state is inherently insulating when it is nonsuperconducting. Moreover, we found that this insulating state is characterized by the peculiar log(1/T) resistivity divergence.4. We elucidated that the charge transfer energy in the CuO_2 plane can be obtained from the temperature dependence of the Hall coefficient measured up to 1000 K. Furthermore, we showed that the Hall coefficient data can be used for disentangling the phase-separated nature of La_2-x_Sr_xCuO_4 in the superconducting doping regime.

人们认识到，由于强烈的电子相关性，高-TC铜酸盐超导体发生了某种电子自组织。同样，在库酸酯中，电子自组织现象似乎位于其特殊的电子状态后面，例如在高磁场下不寻常的绝缘状态或超导间隙的内在不均匀性。该项目通过使用高质量的单晶，尤其是在极端条件下使用高质量的单晶测量的实验，阐明了铜塔中电子自组织现象的各个方面。主要结果如下：1。我们发现了在LA_2-X_SR_XCUO_4中充电的“魔术掺杂分数”的存在，并表明棋盘模型始终解释了观察到的分数。2。 YBA_2CU_3O_Y，LA_2-X_SR-XCUO_4和BI_2SR_2SR_2CACU_XO_ <8+ueutugutive的超低温度导热率的广泛测量值表明，“通用热导电性”的崩溃，这通常是预计D-Wave BCS超级托管。这种崩溃显然与丘比特的特殊超导间隙不均匀性有关。3。通过对YBA_2CU_3O_Y的非执行YBA_2CU_3O_Y的转运性能的超高测量，已知存在自组织的抗性各向异性存在，我们阐明了电子自组织的状态在非耐pperperponconductucconding时固有地绝缘。此外，我们发现这种绝缘状态的特征是特殊的log（1/t）抗性差异4。我们阐明了CUO_2平面中的电荷传递能可以从高达1000 K的霍尔系数的温度依赖性中获得。此外，我们表明，Hall重要数据可用于散发LA_2-X_SR_SR_SR_XCUO_4的相位分离性质。