Charge order and low frequency spin dynamics in lanthanum cuprates revealed by Nuclear Magnetic Resonance

TL;DR

This study uses NMR and NQR techniques to investigate charge order and spin dynamics in lanthanum cuprates, revealing stripe order phenomena and their doping dependence.

Contribution

It provides detailed experimental evidence of charge stripe order and low-frequency spin dynamics in lanthanum cuprates using advanced NMR/NQR measurements.

Findings

Partial wipeout of 17O NMR intensity at stripe ordering temperature

Complete wipeout of 63Cu NMR intensity at the same temperature

Doping-dependent peak in spin lattice relaxation rate, maximal at x ~ 1/8

Abstract

We report detailed 17O, 139La, and 63Cu Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) measurements in a stripe ordered La1.875Ba0.125CuO4 single crystal and in oriented powder samples of La1.8-xEu0.2SrxCuO4. We observe a partial wipeout of the 17O NMR intensity and a simultaneous drop of the 17O electric field gradient (EFG) at low temperatures where the spin stripe order sets in. In contrast, the 63Cu intensity is completely wiped out at the same temperature. The drop of the 17O quadrupole frequency is compatible with a charge stripe order. The 17O spin lattice relaxation rate shows a peak similar to that of the 139La, which is of magnetic origin. This peak is doping dependent and is maximal at x ~ 1/8.