Exotic phases of frustrated antiferromagnet LiCu2O2

TL;DR

This study investigates the complex magnetic phases of LiCu2O2 using high-field NMR spectroscopy and phenomenological modeling, revealing unusual magnetic structures with two-component order parameters and harmonic variations.

Contribution

It introduces a detailed NMR analysis combined with Dzyaloshinskii-Landau theory to identify novel magnetic structures in frustrated antiferromagnet LiCu2O2.

Findings

Identification of magnetic field-induced spectral changes.

Proposal of magnetic structures with two-component order parameters.

Modeling suggests complex magnetic phase transformations.

Abstract

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.