Incommensurate helical magnetic order in LiCu2O2 and NaCu2O2 quasi-one-dimensional compounds

The results of the measurements of the 6, 7Li and 23Na nuclear magnetic resonance (NMR) and 63, 65Cu nuclear quadrupole resonance in LiCu2O2 and NaCu2O2 quasi-one-dimensional compounds with a spin chains in the paramagnetic and magnetically ordered states are presented. The shape of the NMR line below Tc = 24 and 13 K for LiCu2O2 and NaCu2O2, respectively, is characteristic of the incommensurate static modulation of the local magnetic field matching with the incommensurate spiral modulation of the magnetic moments. The differences in the shape of the NMR spectra of 23Na and 7Li are discussed in terms of the features of the crystal structure of LiCu2O2 and NaCu2O2.