Magnetic phase diagram of the frustrated S=1/2 chain magnet LiCu_2O_2

TL;DR

This study investigates the magnetic phase diagram of LiCu_2O_2, revealing novel phase transitions and a high-field collinear spin-modulated phase in a frustrated S=1/2 chain magnet through magnetization and dielectric measurements.

Contribution

First detailed experimental mapping of magnetic phases in LiCu_2O_2, identifying new phase transitions and high-field behavior in a frustrated S=1/2 chain system.

Findings

Observation of spin flop transition for H||a,b

Identification of a second magnetic transition at ~15 T

High-field phase as collinear spin-modulated state

Abstract

We present the results of the magnetization and dielectric constant measurements on untwinned single crystal samples of the frustrated S=1/2 chain cuprate LiCu_2O_2. Novel magnetic phase transitions were observed. A spin flop transition of the spiral spin plane was observed for the field orientations H||a,b. The second magnetic transition was observed at H~15 T for all three principal field directions. This high field magnetic phase is discussed as a collinear spin-modulated phase which is expected for an S=1/2 nearest-neighbor ferromagnetic and next-nearest-neighbor antiferromagnetic chain system.