Evaluation of domain wall displacement into ferromagnetic materials under the influence of external magnetic field
Journal Title: Вісник Тернопільського національного технічного університету - Year 2015, Vol 79, Issue 3
Abstract
The analysis of the theoretical approaches to modeling the domain walls motion in the ferromagnets for the actions of external reversal magnetization field are considered. The energy of a ferromagnetic material as a sum of energy exchange interactions, magnetostatic energy, anisotropy and disorder are described. The most important energetic contribution comes from exchange interactions, which are typically short-ranged and tend to align spins. The magnetostatic energy is due to the interactions between the spins and the external field and to dipole-dipole interactions between different spins. The magnetization in a ferromagnetic material typically has preferential directions corresponding to the crystallographic axis of the material. It is easier to magnetize the sample along the easy directions. This reflects the energy magnetocrystalline anisotropy. The energy disordering displays the microstructure of the material. The presence of randomly distributed non-magnetic inclusions give rise to a magnetostatic contribution, due to the magnetic charges that form at the boundaries of the inclusions. The structural inhomogeneity caused is due to the presence of vacancies, dislocations or magnetic impurities. The equation of total energy domain wall are considered. The equation of the 900 domain walls displacements and distribution of the magnitude jump at the different value the applied field are considered. The 900 domain walls jumps causes of the local magnetostriction phenomenon. It is causes elastic displacements in a ferromagnetic because of volume source of the transformation deformations. This deformation describes the source of magnetoelastic acoustic emission. The amplitude values of the magnetoelastic acoustic emission signal proportional to the transformation deformations and the rate of change volume region of the reversal magnetization. The maximum displacements and magneto-elastic acoustic emission amplitude values can be calculated using this model. It is shown that the magnetoelastic acoustic emission is sensitive to changes in domain structure of ferromagnetic materials.
Authors and Affiliations
Yevgen Pochapskyy, Natalya Melnyk
Keywords
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