The loss of mechanical stability and the critical magnetization of a ferromagnetic particle in an elastomer.

The rotation of a spherical magnetically soft ferromagnetic particle with uniaxial magnetic anisotropy and located in an elastomer through a certain angle under the action of a magnetic field has been studied theoretically. It was found that if the particle loses its mechanical stability, its rotation angle becomes critically dependent on the magnetic field magnitude. The magnetically induced critical rotation of the particle in the elastomer has a magneto-elastic origin and is accompanied by a critical change in the magnetization of the particle multidomain state, as occurs in the case of second-order magnetic phase transitions. The transition of a particle in a soft-elastic elastomer from the multidomain state into a uniformly magnetized one was shown to be independent of the magnitude of the particle magnetic anisotropy field. The particle rotation was found to result in the appearance of a maximum in the field dependence of the magnetic susceptibility.