10.2.2 Behavior in an External Field Parallel to the Chain Axis

If the initial magnetization of the particles is parallel to the axis of the chain and the short axis of the particles, the behavior in zero field is also dominated by the magnetostatic stray field. The demagnetization curves for elliptical and rectangular particles are given in Fig. 10.6. The snapshots of the particles given in Fig. 10.7 shows how the magnetization of the particles at the end of the chain tries to align parallel to the long axis. As soon as the symmetry of this metastable state breaks, the stray field leads to an antiparallel alignment of the magnetization of the neighboring particles. By chance, the particles at the end of the chain choose one or the other direction but in any case the stray field causes the antiparallel alignment of the neighboring particle. Since the particles at the end of the chain chose the same direction, the magnetization of those in the center is parallel.

Figure 10.6: Chain of particles with the initial magnetization parallel to the chain axis.

Figure 10.7: Snapshot of the relaxation process of a chain of six elliptical and rectangular particles with their initial magnetization parallel to the chain axis.

Figure 10.8: Equilibrium magnetization distribution in zero field of a chain of six elliptical and rectangular particles with their initial magnetization parallel to the chain axis.