Evidence for stripe correlations of spins and holes in copper oxide superconductors

Abstract

ONE of the long-standing mysteries associated with the high-temperature copper oxide superconductors concerns the anomalous suppression1 of superconductivity in La2-xBaxCuO4 (and certain related compounds) when the hole concentration x is near 1/8. Here we examine the possibility that this effect is related to dynamical two-dimensional spin correlations, incommensurate with the crystal lattice, that have been observed in La2-xSrxCuO4 by neutron scattering2-4. A possible explanation for the incommensurability involves a coupled, dynamical modulation of spin and charge in which antiferromagnetic 'stripes' of copper spins are separated by periodically spaced domain walls to which the holes segregate5-9. An ordered stripe phase of this type has recently been observed in hole-doped La2NiO4 (refs 10-12). We present evidence from neutron diffraction that in the copper oxide material La1.6-xNd 0.4SrxCuO4, with x Combining double low line 0.12, a static analogue of the dynamical stripe phase is present, and is associated with an anomalous suppression of superconductivity13,14. Our results thus provide an explanation of the '1/8' conundrum, and also support the suggestion15 that spatial modulations of spin and charge density are related to superconductivity in the copper oxides. © 1995 Nature Publishing Group.