Grain boundaries (GBs) exert a substantial effect on the domain structure (DS) and magnetic properties of polycrystalline materials [1-3]. The role of such defects is especially large in the formation of structure and properties of nanomaterials and composites [4,5], in which the relative volumes of grain boundaries and interphase boundaries can exceed 20%. In this work, we report the results of a theoretical investigation into the main features of the spatial distribution of spontaneous magnetization M_s(r), the topology of magnetostatic fields H^m(r) near GBs, and the results of calculations of the shape z(x) of 180^o DWs in plates of triaxial ferromagnets such as silicon iron (~3% Si) with a surface plane (011) in a demagnetized state (at H^e=0). It is shown that in the states of thermodynamic equilibrium Bloch domain walls can bend as a consequence of deviations Δθ(x) of the magnetic moments of atoms m_a from the <100> easy axis under the effect of magnetic stray fields H^m generated by grain boundaries (the μ^* - effect inside magnetic domains near grain boundaries). The magnitudes of the effects studied (the deviations Δθ(x) of the M_s vectors from the easy axes, the magnitudes of the flexures Δz^bend of domain walls, the extensions of the macroscopic zones Δx^bend characterized by inhomogeneous magnetization, as well as the maximum values of the strengths H^m_x of the magnetostatic fields H^m near grain boundaries) increase with decreasing magnetocrystalline anisotropy constant and increasing period of the domain structure 2D.

[1] J.Goodenough, Phys. Rev. 1954. V.95. № 4. P. 917-932.

[2] A.Hubert, R.Schafer, Magnetic Domains: The Analysis of Magnetic Microstructures (Springer, Berlin, 1998. 696 p.).

[3] L.Sheiko, Gh.Brekharya, O.Kulyk, JMMM. 2000. V.215-216. P. 86-88.

[4] G.Herzer, JMMM. 1996.V.157-158, P.133-136.

[5] F.Mazaleyrat, L.K.Varga, JMMM. 2000. V.215-216. P. 253-259.

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1. Calculation of magnetostatic energy F_m of periodic domain structures formed near grain boundaries in plates of triaxial ferromagnets of silicon iron type