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The magnetoresistance of a free-standing permalloy strip was investigated to determine the correlation between magnetoresistive response noise and micromagnetic behavior. The results showed that bias fields had a suppressive effect on the magnetoresistance response noise although it was not totally eliminated. An inherent discontinuity dominated by the applied field was detected.

We have studied pairs of interacting permalloy particles of submicron size using our micromagnetic code based on the finite element method. The hysteretic properties of the pairs are affected by both the placements and the separations between particles. Plateaus are found in the hysteresis loops of most pairs placed side by side or one on top of the other. They correspond to antiferromagnetically aligned states. Most pairs may be brought to a cross-tie wall state. We found that cross-tie wall formation is affected by the shapes of the particles at the ends.

The micromagnetic characteristics of imperfect permalloy particles were investigated to determine the influence of voids and corner shapes. The results showed that particles with semicircular ends featured higher coercivities than those with square ends. When the dimension of a void was substantially less than the exchange length of a sample, the micromagnetic characteristics were not affected.