# Anisotropic Exchange in ${\bf LiCu_2O_2}$

## TL;DR

This study uses ESR measurements to analyze the magnetic anisotropies and exchange interactions in the multiferroic quantum-spin system LiCu$_2$O$_2$, revealing the roles of symmetric and antisymmetric interactions in spin relaxation.

## Contribution

It provides a microscopic analysis of the exchange interactions and anisotropies in LiCu$_2$O$_2$, highlighting the dominant role of symmetric anisotropic and Dzyaloshinskii-Moriya interactions.

## Key findings

- Anisotropies of the g tensor and ESR linewidth are due to crystal-electric field and local exchange geometries.
- Both symmetric anisotropic exchange and Dzyaloshinskii-Moriya interactions dominate spin relaxation.
- The analysis covers a wide temperature range from the Néel temperature to 300 K.

## Abstract

We investigate the magnetic properties of the multiferroic quantum-spin system LiCu$_2$O$_2$ by electron spin resonance (ESR) measurements at $X$- and $Q$-band frequencies in a wide temperature range $(T_{\rm N1} \leq T \leq 300$\,K). The observed anisotropies of the $g$ tensor and the ESR linewidth in untwinned single crystals result from the crystal-electric field and from local exchange geometries acting on the magnetic Cu$^{2+}$ ions in the zigzag-ladder like structure of LiCu$_2$O$_2$. Supported by a microscopic analysis of the exchange paths involved, we show that both the symmetric anisotropic exchange interaction and the antisymmetric Dzyaloshinskii-Moriya interaction provide the dominant spin-spin relaxation channels in this material.