We report on the phase diagram for charge-stripe order in La1.6-xNd0. 4SrxCuO4, determined by neutron and x-ray scattering studies and resistivity measurements. From an analysis of the in-plane resistivity motivated by recent nuclear-quadrupole-resonance studies, we conclude that the transition temperature for local charge ordering decreases monotonically with x, and hence that local antiferromagnetic order is uniquely correlated with the anomalous depression of superconductivity at x approximately 1 / 8. This result is consistent with theories in which superconductivity depends on the existence of charge-stripe correlations.

High-energy photon diffraction is used to investigate the charge ordering previously studied by neutron diffraction in La1.48Nd0.4Sr0.12CuO4. Besides confirming the existence of superlattice peaks due to charge order, the temperature dependence of the peak intensity, width, and position has been determined with improved precision. Furthermore, we show that the scattered intensity has a sinusoidial modulation along c * , consistent with long-range Coulomb interactions between ordered charges within the CuO2 planes.

Superstructure reflections due to the ordering of holes into stripes in La1.45Nd0.4Sr0.15CuO4 have been studied with high energy x-ray diffraction. These reflections have been observed clearly for the first time in a sample which is superconducting at low temperatures (Tc ∼ 10 K). The stripe peaks vanish above 62(5) K whereas the magnetic signal of the stripe ordering which has been seen with neutrons before is already suppressed at ∼ 45 K. Our results confirm that the ordering of spins and holes is driven by the charges as it is found in the case of La1.6−xNd0.4SrxCuO4 at the doping level of x = 0.12.

No abstract

No abstract