Magnetic excitations in cycloidal magnet LiCu2O2 are explored using THz absorption spectroscopy in magnetic fields up to 12 T. Below the spin ordering temperature we observe eight optically active transitions in the spin system of LiCu2O2 in the energy range from 4 to 30 cm−1. In magnetic field the number of modes increases and the electric polarization flop is seen as a change in magnetic field dependence of mode energies. The polarization dependence of two of the modes in zero magnetic field fits the selection rules for the cycloid tilted by θ=41±1∘ from the bc plane. For the remaining six modes electric and magnetic dipole approximations cannot explain the observed polarization dependence. We do not see the electromagnon in the explored energy range although there is evidence that it could exist below 4 cm−1.
@article{arxiv.0904.2329,
title = {Magnetic excitations and optical transitions in the multiferroic spin-1/2 system LiCu$_2$O$_2$},
author = {D. Hüvonen and U. Nagel and T. Rõõm and Y. J. Choi and C. L. Zhang and S. Park and S. -W. Cheong},
journal= {arXiv preprint arXiv:0904.2329},
year = {2015}
}
Comments
4 pages, 4 figures, submitted to PRB for publication as Rapid Communication