POSSIBLE CHARGE AND/OR SPIN ORDERING IN THE Bi-2212, Y-123 AND La-214 PHASES

Abstract

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.

Absence of the impurity-induced magnetic order in the electron-doped high-Tc cuprates Pr0.86LaCe0.14Cu1−y(Zn,Ni)yO4

“…This is interpreted as a result of the strong pinning effect of Zn on the dynamically fluctuating stripes of spins and holes [8,9]. Similar effects of Zn on the Cu-spin dynamics has been observed in the hole-doped Bi 2 Sr 2 Ca 1- [10,11] and YBa 2 Cu 3-2y Zn 2y O 7-δ [12] as well.…”

“…The temperature dependence of the spectra is similar to one another. No impurity-induced slowing down of the Cu-spin fluctuations is detected for moderately oxygen-reduced samples of the small and large δ, which is very different from the results of the hole-doped high-T c cuprates [6][7][8][9][10][11][12]. This may be understood in two ways.…”

“…This may be understood in two ways. First, there may be no dynamically fluctuating stripes of spins and electrons in the electron-doped system, because the dynamical stripes lead to the impurity-induced magnetic order in the hole-doped system [8,9]. Second, Pr 0.86 LaCe 0.14 CuO 4 may be situated in the overdoped regime, because Cu spins fluctuate so fast that the measured lowest temperature of 2 K is too high to detect the slowing down of the Cu-spin fluctuations in the overdoped regime of the hole-doped La 2-…”

Tuning competing orders inLa2−xSrxCuO4cuprate superconductors by the application of an external magnetic

“…µSR results on Zn doped La 2−x Sr x Cu 1−y Zn y O 4 show an enhancement of magnetism in the vicinity of 1/8 doping [9], suggesting that small amounts of nonmagnetic impurities act as pinning centers for dynamical stripe correlations. The observation of similar magnetic anomalies in Zn substituted Bi-2212 and YBa 2 Cu 3 O 6+x seems to indicate that the 1/8-anomaly is not just a specific feature of the La-based compounds, but a general property of HTSC [10,11].…”

μSR study of the Cu-spin dynamics in the electron-doped high-Tc cuprate of Pr0.86LaCe0.14Cu1−(Zn,Ni) O4

“…A lot of experimental results on the impurity effect have been reported for the hole-doped high-T c cuprates [1][2][3], in contrast to those for the electron-doped ones. The difficulty in preparing superconducting samples of good quality in the electron-doped cuprates is one of the reasons.…”