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

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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.