Multiferroicity of CuCrO2 tested by ESR

We have carried out the ESR study of the multiferroic triangular antiferromagnet CuCrO2 in the presence of an electric field. The shift of ESR spectra by the electric field was observed; the observed value of the shift exceeds that one in materials with linear magnetoelectric coupling. It was shown that the low-frequency dynamics of magnetically ordered CuCrO2 is defined by joint oscillations of the spin plane and electric polarization. The results demonstrate qualitative and quantitative agreement with theoretical expectations of a phenomenological model (V.I. Marchenko (2014)).