Elucidation for search of Dynamical Stripe in YBCO by Inelastic Neutron Scattering Method

我们的目的是阐明铜氧化物材料高温超导的基本机理。根据系统的中子散射研究，在单层空穴掺杂LSCO中存在一维“条纹”态的动力学结构。为了在各种超导铜氧化物材料中寻找这种独特的“条纹”，我们对YBCO的典型HTSC化合物进行了类似的中子散射测量。由于CuO链上氧的局部顺序可能会引起相邻CuO_2平面上电子结构的变化，因此这种晶体中的氧控制问题更大。钙替代可能是解决这一难题的一种很有希望的方法。因此，我们无法制备出中子散射实验所需的掺钙镱钴大晶体。相反，我们成功地生长出了大的、单畴的、高质量的、最佳的掺杂YBCO，并首次进行了详细的非弹性中子散射测量。虽然我们没有完成数据分析，但我们至少可以得出新的实验证据，应该可以修改主要出版物中现有的结果。我们还开发了一种新的声子散射实验技术——超高分辨率同步辐射x射线法。目前我们可以得到在超导状态下LSCO中明确声子异常的数据，然后扩展到YBCO中类似的测量。由于还没有生长出大的单晶，我们期望这种方法只适用于Ca掺杂YBCO的散射实验。

We aimed to elucidate the basic mechanism of high temperature superconductiity (HTSC) in Cu oxide materials. According to our systematic neutron scattering investigations, one dimensional dynamical structure of 'stripe' state exists in the single layered hole doped LSCO. In order to search this unique 'stripe' in various superconducting Cu oxide materials, we made similar neutron scattering measurements of the typical HTSC compounds of YBCO. Oxygen control in this crystal is more problematic, since the local order of oxygen in CuO chains may, -create the change in the electronic structure in neighboring CuO_2 plane. Ca substitutiqn may be a promising method to solve this difficult problem for our investigation. As a result, we could not produce any large crystal of Ca doped YBCO necessary for neutron scattering experiments. Instead, we were succeeded in growing large, single domain, and high quality, optimum doped YBCO, and have made detailed inelastic neutron scattering measurements for the first time. Though we don't complete the data analysis, we could yield at least new experimental evidence which should revise the existing results in the major publication. We also develop a new experimental technique of phonon scattering by using the ultra high resolution synchrotron X-ray radiation method. At present we could produce the data showing, unambiguous phonon anomalies in LSCO in superconducting state and then extendto the similar measurements in YBCO. We expect that this method is only applicable experimental method for the scattering experiments of Ca doped YBCO, since the large single crystal has never been grown.