Spin-phonon and magnetostriction phenomena in CaMn₇O₁₂ helimagnet probed by Raman spectroscopy

Abstract

In this letter, we investigated the temperature-dependent Raman spectra of CaMn7O12 helimagnet from room temperature down to 10 K. The temperature dependence of the Raman mode parameters shows remarkable anomalies for both antiferromagnetic and incommensurate transitions that this compound undergoes at low temperatures. The anomalies observed at the magnetic ordering transition indicate a spin-phonon coupling at higher-temperature magnetic transition in this material, while a magnetostriction effect at the lower-temperature magnetic transition.