Cu NQR Study of the Stripe Phase Local Structure in the Lanthanum Cuprates

Abstract

Using Cu nuclear quadrupole resonance (NQR) in Eu-doped La2-xSrxCuO4 we find the evidence of the pinned stripe phase at 1.3 K for 0. 08</=x</=0.18. The pinned fraction increases by 1 order of magnitude near hole doping x = 1/8. The NQR line shape reveals three inequivalent Cu positions: (i) sites in the charged stripe, (ii) nonmagnetic sites outside the stripes, and (iii) sites with a magnetic moment of 0.29&mgr;(B) in the antiferromagnetically correlated regions. A dramatic change of the NQR signal for x>0.18 correlating with the onset of bulk superconductivity corresponds to the depinning of the stripe phase.