The spiral spin state in LiCu2O2
Journal
Journal of the Physical Society of Japan
Journal Volume
83
Journal Issue
1
Date Issued
2014
Author(s)
Chen, M.
Abstract
We studied the spiral spin state of LiCu2O2. Our calculation is based on the physical picture of classical spiral spins and their quantum fluctuation. Comparison with the spectra of the electron spin resonance (ESR) shows that the excitations come from the spin waves. If the magnetic field is applied along the b-axis of the crystal, there are two branches of excitations. The resonance frequency v1 ∼ 30 GHz corresponds to the spin wave states of wave vectors κ = ±Q where Q is the wave vector of spiral spins. However, when the magnetic field is parallel to c-axis, there is only one branch and it comes from the spin wave state of wave vectors κ = 0. Our calculation also shows that the former come from the spin waves in spiral spin configuration and the latter from the collinear spins. We have also analyzed the data of dM/dH. Our calculation shows that the spiral spin axis is parallel to b-axis if there is no applied field. When magnetic field is applied along α- or c-axis the spiral axis remains more or less the same until a critical field is reached. When the field strength reaches the second critical field, all the spins become collinear. These results confirm the assumption that there are two critical fields, Hc1 and Hc2. We further discuss the roles played by anisotropy exchange interaction and Dzyaloshinskii-Moriya interaction and how the spiral spin state in LiCu 2O2. ©2014 The Physical Society of Japan.
Type
journal article