  We have found the 1/8 anomaly, namely, the anomalous suppression of
superconductivity at p (the hole concentration per Cu) = 1/8 in the
excess-oxygen-doped La_1.8_Nd_0.2_Cu_1-y_Zn_y_O_4+\delta_, where the excess
oxygen is doped by the electrochemical technique and the phase separation of
the excess oxygen is suppressed. The 1/8 anomaly has become marked by the 1 %
substitution of Zn for Cu. The muon-spin-relaxation measurements have revealed
that the magnetic correlation develops at low temperatures below about 50 K in
both Zn-free and 1 % Zn-substituted samples with p = 1/8. Clear precession of
muon spins suggesting the formation of a long-range magnetic order has been
observed below 1 K in the 1 % Zn-substituted sample with p = 1/8. These results
are consistent with the stripe-pinning model.
