Acousto-optic diffraction in hematite due to the magnetoelastic modulation of the polarizations of optical modes

Acousto-optic diffraction in the Raman-Nath regime is observed in the α-Fe₂O₃ easy-plane antiferromagnet. This diffraction is caused by the magnetoelastic modulation of the polarizations of normal optical modes propagating along the trigonal axis of the crystal. The diffraction parameters are analyzed as functions of the static magnetic field applied in the basal plane. The intensity of the diffraction wave in fields on the order of the monodomainization field of the samples (H _D ≈ 1.8 kOe), at an acoustic flux power of I _S ～ 7.0 W/cm², was approximately 0.11% of the incident light intensity and its polarization was perpendicular to the polarization of the linearly polarized incident wave. It is shown that the observed intensity is comparable with the intensity of the acousto-optic diffraction in nonmagnetic materials. The results are well described by the theory of acoustooptic diffraction in antiferromagnets {E. A. Turov, Zh. Éksp. Teor. Fiz. 112, 1464 (1997) JETP 85, 797 (1997)]} and confirm its basic conclusions.