Recent experimental work on the 1/8 anomaly in the Bi-2212 and Y-123 phases by our group is reviewed. In the partially Zn-substituted Bi2Sr2Ca1-xCu1-yZny) 2O8+δ, we have found anomalous suppression of superconductivity at x = 0.30 - 0.35, where the hole concentration per Cu in the CuO2 plane, p, ∼ 1/8. Moreover, it has been revealed from the muon spin relaxation (μSR) measurements that the Cu-spin fluctuations exhibit slowing-down behavior at low temperatures singularly in these samples. In Y1-xCaxBa2Cu3O7-δ, the so-called 60 K plateau of Tc has been found not to be correlated with the oxygen content but to be interpreted as being due to the suppression of superconductivity at p ∼ 1/8. The slowing-down behavior of the Cu-spin fluctuations has also been observed singularly at p ∼ 1/8 in the partially Zn-substituted YBa2Cu3-2yZn2y/O7-δ. These results are suggestive of the dynamical stripe correlations of holes and spins tending to be pinned by a small amount of Zn at p ∼ 1/8 in the Bi-2212 and Y-123 phases as well as in the La-214 phase. Accordingly, we conclude that, the 1/8 anomaly is common to all high-Tc cuprates with the CuO2 plane.
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