Our recent experimental studies on the 1/8 anomaly in the Bi-2212 and Y-123 phases and on the new anomaly at x = 0.21 in La2-xSr x Cuiy ZnyO4 are reviewed. In the Zn-substituted Bi-2212 and Y-123 phases, we have found anomalous suppression of superconductivity at p (the hole concentration per Cu in the CuCh plane)-1/8, and it has been found from the muon spin relaxation (// SR) measurements that the magnetic correlation between Cu spins is enhanced singularly at p ~ 1/8. Furthermore, we have found marked suppression of superconductivity singularly at x = 0.21 in the 1% Zn-substituted single-crystals of La2-xSr x Cuiy ZnyO4, and it has been found from the // SR measurements that the magnetic correlation is also enhanced at x = 0.21. These results suggest that the dynamical stripe correlations of holes and spins exist in the Bi-2212 and Y-123 phases as well as in the La-214 phase and that they tend to be pinned by Zn, leading to the suppression of superconductivity. If this tendency is the case in a wide range of p, it is possible to understand the universal results in the high-T c cuprates that Zn is a strong scatterer and that the Zn substitution markedly suppresses superconductivity.

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Zero-field ͑ZF͒ and longitudinal-field ͑LF͒ muon spin relaxation (SR) measurements have been carried out in the overdoped single crystals of La 2Ϫx Sr x Cu 1Ϫy Zn y O 4 with xϭ0.21, yϭ0 and 0.01. In the case of the Zn-substituted crystal with xϭ0.21 and yϭ0.01 in which the high-T c superconductivity is almost suppressed, the ZF-and LF-SR measurements have revealed the existence of a static ordered state of Cu spins at low temperatures below 2 K. No clear coherent precession of the muon spin has been observed down to 20 mK. Slowing down of the Cu-spin fluctuations has also been observed in the non-Zn-substituted crystal with x ϭ0.21 and yϭ0 at low temperatures below about 0.8 K in ZF, indicating that the observed magnetic anomaly is an intrinsic property at xϭ0.21. These SR results suggest a strong possibility of the existence of a spin/charge ordered state at xϭ0.21 in the overdoped region.

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Our recent experimental studies on the so-called 1/8 anomaly in the Bi-2212 and Y-123 phases and also on the new anomaly in the overdoped region of the La-214 phase are reviewed. In the partially Zn-substituted Bi-2212 and Y-123 phases, we have found anomalous suppression of superconductivity (SC) at p (the hole concentration per Cu in the Cu02 plane) ~ 1/8, and it has been found from the muon-spin-relaxation (/^SR) measurements that the magnetic correlation between Cu spins is enhanced singularly at p ~ 1/8. Furthermore, we have found giant suppression of SC singularly at x = 0.21 in the 1% Zn-substituted single-crystals of La2-xSr x Cui_ 1/ Zn 3/ 04 (LSCZO), and it has been found from the /xSR measurements that the magnetic correlation is also enhanced at x = 0.21. These results suggest that the dynamical stripe correlations of holes and spins exist in the Bi-2212 and Y-123 phases as well as in the La-214 phase and that they tend to be pinned by a small amount of Zn, leading to quasi-static stripe order and the suppression of SC at p ~ 1/8 in the Bi-2212, Y-123, La-214 phases and also at a; = 0.21 in LSCZO. If this tendency is the case in a wide range of p> it is possible to understand the universal experimental results in the high-T c cuprates that Zn is a strong scatterer in the unitarity limit and that the Zn substitution markedly suppresses SC.