μSR Study on the Dynamics of Charges and Spins in the High-T_c Oxides, and Development of High-Pressure μSR

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(1) μSR on the high-Tc oxidesIn order to investigate the dynamics of the stripe correlations of spins and holes, μSR measurements have been carried out on in the high-Tc oxides of La-, Bi2212- and-systems. It has been found from the non-magnetic impurity dependence on the La-system around the hole concentration of 1/8 per Cu that the dynamical stripes are statically stabilized by a small amount non-magnetic impurities (less than 1%) and destroyed by a large amount non magnetic impurities (more than 1%). From μSR measurements on the La-system around 100 K, the slowing down of the Cu-spin fluctuations that is expected to be caused by the stabilization of the dynamical stripes has been detected. Since the temperature where the stabilization of the Cu-spin fluctuations starts to be observed by the μSR measurement is consistent to the temperature where carriers tend to be localized, our result reveals that the suppression of the Cu-spin fluctuations couples with the localization of carriers.From μSR measurements on the Bi2212- and Y-systems, it has been found that the Cu-spin fluctuations are anomalously suppressed by a small amount non-magnetic impurities around the hole concentration of 1/8 per Cu. This result suggests the existence of the dynamical stripes in both systems.(2)High pressure μSRDesign and development works of a high-pressure cell for μSR measurements have been done. CuBe was chosen as the material of the cell. The maximum pressure was designed to be 1 Gpa. The cell was designed to be matched with the existing cryostat. The cell was manufactured and tested using the muon beam with a high momentum. We are planning to use the cell for real experiments after the pressure calibration at low temperatures.