Cascade generation of a phase conjugate wave in a magnetoordered acoustic medium

The cascade generation of second acoustic harmonics accompanied by simultaneous parametric wave phase conjugation in an α-Fe2O3 antiferromagnetic crystal in a transverse electromagnetic field is studied experimentally and theoretically. The necessary conditions for generation upon varying the direction of magnetization relative to the crystallographic axes and the direction of transverse sound wave propagation are determined. The observed effect is caused by magnetoelastic interaction and is described using the theory of giant effective elastic anharmonicity.