Analysis of optical magnetoelectric effect in ${\text{GaFeO}}_{3}$

Analysis of optical magnetoelectric effect in ${GaFeO}_{3}$

Jun-ichi Igarashi and Tatsuya Nagao

Phys. Rev. B 80, 054418 – Published 31 August 2009

Abstract

We study the optical-absorption spectra in a polar ferrimagnet ${GaFeO}_{3}$ . We consider the $E 1$ , $E 2$ , and $M 1$ processes on Fe atoms. It is shown that the magnetoelectric effect on the absorption spectra arises from the $E 1 − M 1$ interference process through the hybridization between the $4 p$ and $3 d$ states in the noncentrosymmetric environment of Fe atoms. We perform a microscopic calculation of the spectra on a cluster model of ${FeO}_{6}$ consisting of an octahedron of O atoms and an Fe atom displaced from the center with reasonable values for Coulomb interaction and hybridization. We obtain the magnetoelectric spectra, which depend on the direction of magnetization, as a function of photon energy in the optical region 1.0–2.5 eV, in agreement with the experiment.