2003/09/12 by K. D. Belashchenko
Materials Science · Physics and Astronomy · #Anisotropy #Composite material #Condensed matter physics #Domain wall (magnetism) #Ferromagnetism #Magnet #Magnetic Properties and Applications #Magnetic Properties of Alloys #Magnetic anisotropy #Magnetic field #Magnetic properties of thin films #Magnetization #Materials science #Optics #Phase (matter) #Physics #Stiffness #Tetragonal crystal system #cond-mat.mtrl-sci
paper · pdf · doi:10.1016/j.jmmm.2003.09.017
published as J. Magn. Magn. Mater. 270, 413 (2004). · 9 pages, 2 figures, revtex4; to be published in J. Magn. Magn Mater
arxiv created 2003/09/12 · openalex publication_date 2003/11/17 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Using the spin-spiral formulation of the tight-binding linear muffin-tin orbital method, the principal components of the exchange stiffness tensor are calculated for typical hard magnets including tetragonal CoPt-type and hexagonal YCo5 alloys. The exchange stiffness is strongly anisotropic in all studied alloys. This anisotropy makes the domain wall surface tension anisotropic. Competition between this anisotropic surface tension and magnetostatic energy controls the formation and dynamics of nanoscale domain structures in hard magnets. Anisotropic domain wall bending is described in detail from the general point of view and with application to cellular Sm-Co magnets. It is shown that the repulsive cell-boundary pinning mechanism in these magnets is feasible only due to the anisotropic exchange stiffness if suitably oriented initial pinning centers are available. In polytwinned CoPt-type magnets the exchange stiffness anisotropy controls the orientation of macrodomain wall segments. These segments may reorient both statically during microstructural coarsening and dynamically during the macrodomain wall splitting in external field. Reorientation of segments may facilitate their pinning at antiphase boundaries.