|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Materials Science for High-Performance Permanent Magnets
||Demagnetizing Fields and Magnetization Reversal in Permanent Magnets
||Johann Fischbacher, Lukas Exl, Thomas Schrefl
|On-Site Speaker (Planned)
Micromagnetic simulations give a deep insight into the mechanisms that cause magnetization reversal at external fields well below the anisotropy field. Comparing finite element micromagnetic simulations with a simple model for magnetization reversal, we show how magnetostatic interactions trigger magnetization reversal. Magnetization reversal starts, when the total internal field exceeds the Stoner-Wohlfarth switching field locally. Scanning the magnet grain by grain, we create maps of the local coercive field within a permanent magnet. The position of the weak spots within a magnet depends on the nature of the grain surfaces and on the temperature. Grain boundary diffusion shifts the nucleation site from the grain surface towards to core of the grain. With increasing temperature, the magneto-crystalline anisotropy decreases faster than the demagnetizing field. Consequently, demagnetizing effects dominate magnetization reversal at high temperature. Work supported by the Austrian Science Fund (F41-12), EC (H2020 Novamag), NEDO (MagHEM), JST (CREST).