7Li NMR spectra were measured in a magnetic ﬁeld up to 17 T at temperatures 5–30 K on single crystalline LiCu2O2. Earlier reported anomalies on magnetization curves correspond to magnetic ﬁeld values where we observe changes of the NMR spectral shape. For the interpretation of the ﬁeld and temperature evolutions of our NMR spectra, the magnetic structures were analyzed in the frame of the phenomenological theoretical approach of the Dzyaloshinskii-Landau theory. A set of possible planar and collinear structures was obtained. Most of these structures have an unusual conﬁguration; they are characterized by a two-component order parameter and their magnetic moments vary harmonically not only in direction, but also in size. From the modeling of the observed spectra, a possible scenario of magnetic structure transformations is obtained.
- quantum magnetism