Berlin 2005 – wissenschaftliches Programm

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MA: Magnetismus

MA 4: Mikromagnetismus / Computational Magnetism

MA 4.3: Vortrag

Freitag, 4. März 2005, 12:30–12:45, TU H1028

Micromagnetism and the microstructure of cell boundaries in nanostructured Sm₂Co₁₇ based magnets — •H. Kronmüller and D. Goll — Max-Planck-Institut für Metallforschung, Stuttgart, Germany

High-quality permanent magnets on the basis of rare earth intermetallic compounds achieve large coercive fields either by large nucleation fields or by strong pinning forces of domain walls (dws). Sm₂Co₁₇ based magnets are characterized by pinning of dws at the cell walls of 1:5 structure within the pyramidal nanostructure. For a micromagnetic calculation of the interaction force between a dw and an extended phase boundary we consider a space dependent magnetocrystalline anisotropy constant, K₁(r), and an exchange constant, A(r), which vary over a distance, d, from the values K₁^2:17, A^2:17 of the 2:17 matrix phase to a value K₁^1:5, A^1:5 of the 1:5 cell wall phase. Using the K₁(r) profiles as determined by EDX measurements the coercive field due to dw pinning is determined self consistently by numerical methods as a function of the profile parameters taking into account the modification of the spin structure of the dw by the space dependent material parameters.