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The results of a study of magnetoactive elastomers (MAEs) consisting of an elastomer matrix with embedded ferromagnetic particles are presented. A continuous critical bending induced by the magnetic field, characterized by a critical exponent for the bending magnitude, and the derivative of which has a singularity in the critical region is reported for the first time. The mechanical stability loss and the symmetry reduction of the magnetic state, which are interrelated with each other, take place at the critical point. The magnetization in the high-symmetric state (below the critical point) is directed along the magnetic field and the torque is absent. Above the critical point, the magnetization and the magnetic field are noncollinear and there arises a torque, which is self-consistent with the bending. The magnetic field dependence of the MAE bending was found to have a hysteresis, which is associated with the magneto-rheological effect. The shape memory effect was also obtained for the MAE bending in a cycle consisting of magnetization, cooling (at H ≠ 0), and heating (at H = 0). The influence of the critical glass transition temperature of the matrix, as well as its melting/solidification temperature, on the magnetic shape memory effect was studied.

Ferromagnetic resonance properties of F1/f/F2/AF multilayers, where weakly ferromagnetic spacer f is sandwiched between strongly ferromagnetic layers F1 and F2, with F1 being magnetically soft and F2-magnetically hard due to exchange pinning to antiferromagnetic layer AF, are investigated. Spacer-mediated exchange coupling is shown to strongly affect the resonance fields of both F1 and F2 layers. Our theoretical calculations as well as measurements show that the key magnetic parameters of the spacer, which govern the ferromagnetic resonance in F1/f/F2/AF, are the magnetic exchange length (Λ), effective saturation magnetization at T  =  0 (m0) and effective Curie temperature (T(C)(eff)). The values of these key parameters are deduced from the experimental data for multilayers with f  =  Ni(x)Cu(100-x), for the key ranges in the Ni-concentration (x = 54 ÷ 70 at. %) and spacer thickness (d = 3 ÷ 6 nm). The results obtained provide a deeper insight into thermally-controlled spin precession and switching in magnetic nanostructures, with potential applications in spin-based oscillators and memory devices.

In this work, we carry out the analysis of the resonance absorption of electromagnetic radiation for the system in which para- and ferromagnetic phases coexist over a wide temperature region. It is found that taking account of the mutual influence of coexisting phases gives rise to the appearance of substantial changes in the curves of resonance absorption and values of resonance fields, as well as to making the geometry of a phase distribution dependent on an external magnetic field. Near the temperature boundaries of the phase coexistence region, the expressions for description of the curves of the dispersive absorption of electromagnetic radiation are obtained and the rules of the behaviour of the resonance fields for each of the phases are specified. As follows from the calculations, the resonance field for the paramagnetic phase becomes dependent on the shape of the sample, the saturation magnetization and the fraction of ferromagnetic phase. It is shown that the character of magnetic resonance spectra and the features of their temperature change agree well with the experimental data, obtained by various groups of researchers on the single crystalline and polycrystalline samples of doped perovskite manganites.