Influence of domain structure on some dynamic properties of ferromagnets

Abstract

A review is presented of theoretical investigations into the influence of domain structure and dynamic behaviour of domain walls on some low- and high-frequency properties of ferromagnetic materials, The effect of dynamic bowing of domain walls on electromagnetic losses in electrical steel is analyzed in detail. The theories of Pry, Bean and Bishop are generalized to explain experimentally observed nonlinear dependence of eddy-current power losses on frequency and wall spacing. A study is made of the influence of domain structure on the parametric excitation of spin waves with account being taken of domain wall structure. It is shown that the lowest parametric excitation threshold corresponds to spin waves within domain walls and that the parametric excitation effect is rather sensitive to domain wall structure. The influence of a characteristic domain structure arising on the basis of a twinning structure of magnetically ordering alloys on the Mössbauer spectra is analyzed. It is shown that the observed special features of these spectra may be explained on the basis of this domain structure.