Terahertz time-domain spectroscopy was performed to directly probe the low-energy (1-5 meV) electrodynamics of triangular lattice antiferromagnets CuFe1-xGaxO2 (x = 0.00, 0.01, and 0.035). We discovered an electromagnon (electric-field-active magnon) excitation at 2.3 meV in the paraelectric up-up-down-down collinear magnetic phase, while this electromagnon vanishes in the ferroelectric helimagnetic phase. Anti-correlation with noncollinear magnetism excludes the exchange-striction mechanism as the origin of dynamical magnetoelectric coupling, and hence evidences the observation of spin-orbit coupling mediated electromagnon in the present compound.
@article{arxiv.1008.4709,
title = {Electromagnons in the spin collinear state of a triangular lattice antiferromagnet},
author = {S. Seki and N. Kida and S. Kumakura and R. Shimano and Y. Tokura},
journal= {arXiv preprint arXiv:1008.4709},
year = {2015}
}
Comments
5 pages, 5 figures. Accepted in Physical Review Letters