Acoustic resonances in antiferromagnet FeBO3

Size acoustic resonance, which had been observed in basal plates of an easy-plane antiferromagnet FeBO3, was investigated theoretically. It was shown that experimental effects of resonances’ shift in magnetic field are the result of magnetic birefringence of sound and hybridization of acoustic modes in the inhomogeneously magnetized sample. Our consideration was based on the previously suggested model that takes into account nonuniform magnetic anisotropy induced by experimental boundary conditions.