μSR study of the Cu-spin dynamics in La_2-xSr_xCu_1-yZn_yO₄

In order to clarify the effect of non-magnetic impurities on the dynamics of the Cu spin, muon-spin relaxation measurements have been carried out on the Zn-substituted La_2-xSr_xCu_1-yZn_yO₄ with x = 0.13, changing the Zn concentration (0 ≤ y ≤ 0.10). Although the Cu spins at y = 0 have been confirmed to be in the paramagnetic state down to at least 2 K, clear muon-spin precession has been observed at the same temperature at y = 0.01. This muon-spin precession has disappeared at y ≥ 0.05 and the muon-spin depolarization at low temperatures has become small with increasing y at y > 0.01, indicating that the magnetic correlation between Cu spins becomes weaker as the value of y increases at y > 0.01. The present result proves that a small amount of non-magnetic impurities operate to statically stabilize the dynamical stripe correlations of spins and holes but a large quantity of non-magnetic impurities destroy the stripe correlations themselves.