INVERSE ME EFFECT IN A MAGNETOELECTRIC COMPOSITE CONSISTING OF A PIEZOELEMENT AND A WEAK FERROMAGNET OF F<sub>e</sub>BO<sub>3</sub> AS A FERROMAGNETIC PHASE
The multiferrodal system "piezoelectric element - weak ferromagnet FeBO<sub>3</sub>" is studied. The piezoelectric phase with piezoceramics - zirconate titanate lead ZTS-19, and the magnetically ordered phase - a single crystal of a weak ferromagnet, such as iron borate - FeBO<sub>3</sub>. The choice of this ferromagnetic phase is due to the fact that these weak ferromagnets are materials having a record high remagnetization rate, the main acting mechanism of which is the velocity of domain walls with a value many times greater than the speed of propagation of elastic vibrations in them. It is important to note that at transonic speeds and some others, the motion of the domain boundary becomes strongly nonstationary, which may indicate a resonance mechanism for transferring the kinetic energy of its motion to both the elastic and magnetic subsystems. The paper presents the results of an experimental investigation of domain-wall motion caused by bending vibrations in a platelet sample of a single crystal of a weak ferromagnet (fixed on a piezoceramic plate made from a CTS-19) resonantly excited by a piezoelectric when an alternating voltage is applied to it. The measurements are based on the modulation passed through a plate of a weak ferromagnet of iron borate laser radiation (due to the magneto-optical Faraday effect). Dependences of the amplitude of the oscillations of the domain boundary on the amplitude of the oscillations of the sample under the action of an alternating voltage on the piezoelectric ceramics of ZTS-19 at resonant frequencies are obtained. The effect of a constant magnetic field oriented perpendicular to the basal plane of a plate-like sample of a weak ferromagnet on the dynamic behavior of the domain wall is studied. A model system of a magnetoelectric element in the form of a two-layer piezoelectric-weak ferromagnetic structure is proposed. It is established that the motion of the domain boundary in weak ferromagnets at supersonic speeds, being essentially nonlinear, leads to the appearance of new magnetoelectric effects, which are of purely scientific and of great practical interest. This work presents the experimental data on how flexural vibrations in an iron borate plate influence its domain structure. The effect of the constant magnetic field applied perpendicularly to the basic plane of a crystal on dynamics of the domain walls at flexural vibrations of a sample in the field of elastic deformations is investigated.