Local magnetic order vs superconductivity in a layered cuprate

We report on the phase diagram for charge-stripe order in La1.6-xNd0.4SrxCu O4, determined by neutron and x-ray scattering studies and resistivity meas urements. From an analysis of the in-plane resistivity motivated by recent nuclear-quadrupole-resonance studies, we conclude that the transition tempe rature for local charge ordering decreases monotonically with x, and hence that local antiferromagnetic order is uniquely correlated with the anomalou s depression of superconductivity at x approximate to 1/8. This result is c onsistent with theories in which superconductivity depends on the existence of charge-stripe correlations.