Single particle

  Figure 1 shows the distribution of hard magnetic Nd₂Fe₁₄B (red) and soft magnetic Fe₃B (blue) grains in the particle.

For simulation hex_Ia1m1 a finite element mesh of 637 nodes and 2160 elements has been chosen. The edge length of a single element is 3.33 nm which is twice the exchange length of hard and half that of soft grains.

The anisotropy axes of the grains are uniformly distributed, however the elongation of the hexahedrons causes shape anisotropy.

Simulation hex_Ia1m2 was performed with a finite element mesh of 2541 nodes and 10000 elements. The edge length of a single element is 2 nm which comparable with the exchange length of hard grains and only a third of soft grains.

The same distribution of anisotropy axes as for simulation hex_Ia1m1 has been chosen.

Simulation hex_Ia2 used again the fine finite element mesh. The anisotropy axes and all other material parameters as well as the finite element mesh are equal to those of the left particle in simulation hex_Hm2. Thus, the results can be compared with the latter and indicate the influence of the second particle. Compare figures 4 (left particle), 5 (right particle), 8, and the left particle in 10.

Analogously hex_Ia3 is equal to the right particle in simulation hex_Hm2.

    

Figure 1: Finite element meshes and grain distribution of hex_Ia1

The anisotropy axes of hard grains and normals on easy planes of soft grains are indicated by arrows in figure 3. The arrows are projected into the cut plane (figure 2) and normalized. Thus, information about its direction in the third dimension is lost, but its direction in the cut plane better visible.

  

Figure 2: Cut planes of the easy axes, remanent, and coercive state plots of hex_I

  

Figure 3: Easy axes of hex_Ia1

    

Figure 4: Easy axes of hex_Ia2

    

Figure 5: Easy axes of hex_Ia3