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

Abstract

We report detailed O-17, La-139, and Cu-63,Cu-65 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-x Eu0.2Sr (x) CuO4. We observe a partial wipeout of the O-17 NMR intensity and a simultaneous drop of the O-17 electric field gradient (EFG) at low temperatures where the spin stripe order sets in. In contrast, the Cu-63,Cu-65 intensity is completely wiped out at the same temperature. The drop of the O-17 quadrupole frequency is compatible with a charge stripe order. The O-17 spin lattice relaxation rate shows a peak similar to that of the La-139, which is of magnetic origin. This peak is doping dependent and is maximal at x a parts per thousand 1/8.