Raman scattering due to a one-magnon excitation process in ${\rm MnV_2O_4}$

TL;DR

This paper explains the unconventional Raman scattering observed in MnV2O4 at low temperatures by proposing a new one-magnon excitation mechanism specific to noncollinear spin states caused by geometrical frustration.

Contribution

The paper introduces a novel one-magnon Raman scattering mechanism applicable to noncollinear spin structures, explaining experimental features in MnV2O4.

Findings

Unconventional Raman peaks are explained by the proposed one-magnon process.

Selection rules and peak positions match experimental observations.

The mechanism may be relevant to other noncollinear spin materials.

Abstract

Unconventional peak structure in the Raman spectra due to magnon excitation at low temperature is observed in spinel magnet ${\rm MnV_2O_4}$, 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 ${\rm MnV_2O_4}$ 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.