Unconventional peak structure in the Raman spectra due to magnon excitation at low temperature is observed in spinel magnet MnV2O4, where a noncollinear spin state is realized by geometrical frustration. We propose a new mechanism to induce such a Raman scattering process due to a one-magnon excitation of the noncollinear spin state. Novel features of the scattering such as selection rules and peak position observed experimentally in MnV2O4 can be explained quite naturally by considering the present one-magnon process. We also discuss that such one-magnon process may exist in various materials with noncollinear spin structures.
@article{arxiv.1012.4073,
title = {Raman scattering due to a one-magnon excitation process in ${\rm MnV_2O_4}$},
author = {S. Miyahara and K. Takubo and T. Suzuki and T. Katsufuji and N. Furukawa},
journal= {arXiv preprint arXiv:1012.4073},
year = {2010}
}