Comparing OOMMF and magpar

Figure 5.12 shows results computed during the simulation of a half-sphere of diameter 50nm using two different simulation packages that employ the finite difference method (Donahue and Porter, 1999) and the hybrid finite element/boundary element method (Scholz et al., 2003a) respectively. There is good agreement between the two packages.

The results obtained from both OOMMF (FD method) and magpar (hybrid FE/BE method) display an energy barrier which is overcome when $B_x$ is below 50mT. Additionally, reversible behaviour around $B_x=0$ is present in both cases.

The slight aberration in the hysteresis loop for the hybrid FE/BE case is caused by a slight shift in the magnetisation towards the centre of the sample (figure 5.10, point B), present in the simulation as a result of the improved shape resolution over the FD case.