NMR Evidence for Charge Inhomogeneity in Stripe Ordered La_{1.8-x}Eu_{0.2}Sr_{x}CuO_4

TL;DR

This study uses ^{17}O NMR to provide microscopic evidence of charge inhomogeneity in stripe-ordered La_{1.8-x}Eu_{0.2}Sr_{x}CuO_4, revealing spatial charge variations below 80K.

Contribution

It presents direct NMR evidence for charge inhomogeneity in stripe-ordered cuprates, highlighting the spatial distribution of charges in the material.

Findings

NMR signal decreases below 80K indicating charge inhomogeneity.

Evidence of charge segregation between domain walls and insulating regions.

Charge distribution becomes spatially inhomogeneous at low temperatures.

Abstract

We report ^{17}O Nuclear Magnetic Resonance (NMR) results in the stripe ordered La_{1.8-x}Eu_{0.2}Sr_{x}CuO_4 system. Below a temperature T_q ~ 80K, the local electric field gradient (EFG) and the absolute intensity of the NMR signal of the planar O site exhibit a dramatic decrease. We interpret these results as microscopic evidence for a spatially inhomogeneous charge distribution, where the NMR signal from O sites in the domain walls of the spin density modulation are wiped out due to large hyperfine fields, and the remaining signal arises from the intervening Mott insulating regions.