Fine structure of Gakel’–Turov oscillations in iron borate

Acoustic resonances in antiferromagnet FeBO3

“…It proved possible to analyze the experimental dependences o rez (H) [2] on the basis of our models [3,4] that describe the peculiarities of birefringence of sound in this crystal. The theory of magnetic linear birefringence of transverse sound in a trigonal easy-plane antiferromagnet with weak ferromagnetism was developed in the work [5].…”

“…For adequate description of sound birefringence effects in the crystals of Iron Borate type, it is therefore necessary to allow for the boundary conditions. Let us consider the following simplest model [3,4]. Deformations in the crystal, caused by mechanical boundary conditions, lead through magnetoelastic coupling to the appearance of induced uniaxial magnetic anisotropy in the basal plane.…”

“…To interpret weakly magnetic resonances [2] it is necessary to elaborate our basal-anisotropic model, making it more realistic [3,4]. So, we will assume that the deformations, caused by the boundary conditions, are inhomogeneous along the axis C 3 of the crystal: they decrease from the surface to the sample center.…”

“…In the inhomogeneous case for calculation of the amplitude of an acoustic wave passed through the crystal it is convenient to use the Jones matrix method known in optics [3,4]. One may imagine the crystal plate as being divided into n layers parallel to the basal plane with the uniform anisotropy in each layer.…”

Acoustic birefringence at electromagnetic excitation of sound in iron borate crystals

“…Для этого типа образцов нами были обнаружены существенные отличия теории АД [2] и экспери-мента. Их удалось объяснить наличием эффектов наведенной магнитной поверхностной анизотро-пии, вызванной механическими граничными усло-виями, и блочной структуры образцов [4]. Задача данных исследований состояла в изучении эф-фекта АД в совершенном монокристалле FeBO 3 с минимальным влиянием механических напря-жений со стороны акустических контактов на магнитное состояние поверхности образца, т. е. при бесконтактном электромагнитном возбужде-нии звука (ЭМВЗ) в монокристаллическом образ-це [5].…”