A problem of the equilibrium orientation of an elongated solid particle put inside a uniformly aligned nematic liquid crystal is studied. The particle is assumed to be sufficiently large so that the orientational distortions it causes may be treated in the framework of the continuum theory. Three kinds of anchoring of nematic material on the particle surface are considered: two of the planar, and one of the homeotropic type. We prove that, depending on the anchoring strength, the stable orientation of the particle major axis may be either perpendicular (weak anchoring) or parallel (strong anchoring) to the unperturbed director of the liquid-crystalline domain. The dimensionless parameter controlling the situation is the ratio ω of the transverse size of the particle to the extrapolation length of the nematic material. The transition from the perpendicular to the parallel orientation of the particle takes place at ω∼1.

The theory of ferromagnetic resonance (FMR) in an assembly of single-domain uniaxially anisotropic particles is being applied to suspensions. The approach used has, as its basis, the independent-grain model once proposed for the description of FMR in polycrystals. We surmise that the basic assumptions of this model are also appropriate for composites of fine magnetic particles. With regard to the specific properties of the systems in question, we extend the model taking into account (i) the thermofluctuational effects (superparamagnetism) and (ii) the orientational mobility of the particles which leads to the change of the orientational distribution of their anisotropy axes under the influence of the applied field. The joint action of these effects imparts some specific features to the FMR spectra of a magnetic suspension. For example, in a certain temperature range two peak absorption lines must occur.

The origin of the so called magnetostriction effect, i.e., the deformation of a soft magnetic elastomer (SME) in response to a uniform magnetic field is discussed. We note that up to now there exists a number of cases, where the theory is unable to explain the facts well established for real SMEs. In our view, the essential issue, formerly not adequately accounted for, is the type of structural short-range order in the magnetic microparticle assembly. Two-dimensional model problems are formulated and solved, which demonstrate the validity of the hypothesis.