Muon-spin-relaxation study of the Cu-spin dynamics in electron-doped high-Tc superconductor Pr0.86LaCe0.14Cu1-yZnyO4_
Abstract
Muon-spin-relaxation (muSR) measurements have been performed for the partially Zn-substituted electron-doped high-Tc superconductor Pr0.86LaCe0.14Cu1-yZnyO4+alpha-delta with y=0-0.05 and the reduced oxygen content delta=0-0.09, in order to investigate nonmagnetic Zn-impurity effects on the Cu-spin dynamics. For all the measured samples with delta=0.01-0.09, it has been found that a fast depolarization of muon spins is observed below 100 K due to the effect of Pr3+ moments and that the muSR time spectrum in the long-time region above 5 mu-sec increases with decreasing temperature at low temperatures below 30 K possibly due to slowing down of the Cu-spin fluctuations assisted by Pr3+ moments. No Zn-induced slowing down of the Cu-spin fluctuations has been observed for moderately oxygen-reduced samples with delta=0.04-0.09, which is very different from the muSR results of La2-xSrxCu1-yZnyO4. The possible reason may be that there are no dynamical stripe correlations of spins and electrons in the electron-doped high-Tc cuprates or that the effect of Pr3+ moments on the muSR spectra is stronger than that of a small amount of Zn impurities.