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Why Refinement?

The accuracy of the solutions of FE calculations strongly depends on the discretization of the domain in space. The aim of a good discretization is to keep the resulting error constant over the whole domain. However, in hard magnetic materials the magnetization is almost uniform within domains whereas it is highly non-uniform in domain walls, near vortices or grain boundaries. A too coarse mesh of finite elements cannot resolve these structures which leads to the collapse of domain walls [1]. In Nd2Fe14B 180 degree domain walls have a typical thickness of 5 nm.

Domain wall

  

Nucleation Problem

  
Dimensions: 200x200x8 nm Dimensions: 200x200x20 nm Dimensions: 200x200x20 nm Dimensions: 200x200x20 nm
Nodes: 3897 Nodes: 242 Nodes: 2655 Nodes: 7803
Elements: 18700 Elements: 500 Elements: 11070 Elements: 25000
Werner Scholz