10.2 Chain of Particles

The behavior of a chain of isolated elliptical nanoparticles is strongly influenced by the magnetostatic stray fields. The demagnetization curves are given in Fig. 10.4. The external field is parallel to the long axis of the particles. If the particles are initially magnetized parallel to each other and the long axis of the particles, the magnetization reversal occurs at an external field of 72 kA/m. However, if the magnetization of each particle is initially antiparallel to that of its neighbors, that particle at one end of the chain, whose magnetization is antiparallel to the external field, reverses at 87 kA/m. The two other particles inside the chain, whose magnetization is antiparallel to the external field, reverse at 104 kA/m. Thus, the stray field stabilizes the antiparallel magnetized particles and increases the switching field by 44%. Snapshots of the magnetization reversal process are shown in Fig. 10.3.

Figure 10.3: Snapshot of the magnetization reversal process of a chain of six elliptical particles.

[Initially parallel magnetization.]

[Initially antiparallel magnetization.]