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

TL;DR

This study uses Cu NQR to investigate the local structure of stripe phases in La-based cuprates, revealing how stripe pinning and depinning relate to doping levels and superconductivity onset.

Contribution

It provides detailed NQR evidence of stripe phase pinning, its doping dependence, and the correlation with superconductivity in Eu-doped La_{2-x}Sr_xCuO_4.

Findings

Stripe phase is pinned at moderate doping levels.

Pinned stripe fraction increases near x=1/8.

Depinning occurs at doping levels above 0.18, correlating with superconductivity.

Abstract

Using Cu NQR in Eu-doped La_{2- x}Sr_xCuO_4 we show the evidence of the pinned stripe phase for moderate doping at 1.3K. The pinned fraction increases by one order of magnitude near hole doping x=1/8. The NQR lineshape reveals three inequivalent Cu positions: i) sites in the charged stripe; ii) nonmagnetic sites outside the stripes; iii) sites with a magnetic moment of 0.29 Bohr magnethon in the AF 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. .