Multidomain particles

Fig. 12. Total energy vs particle diameter for single- and multidomain particles.

In Figure 13 the relation between the intrinsic coercivity and the particle diameter dis given. The figure is based on a described model (35). The maximum is found around the critical particle diameter. In general the particle diameter and size is not very well defined. For the multidomain particles (d > ) the is smaller than the intrinsic anisotropy field of the particle. Nucleation effects cause a decrease in as the increases. This behavior is... 

In multidomain particles each domain is separated from another by the Bloch wall, where... 

Fig. 13.1.2 Schematic picture of domain structures of magnetic particles (a) superpara-magnetic particles (b) single-domain particle (c) multidomain particle.

For Co particles, 9 nm and for Nd2Fei4B particles, Rc 15 nm. Singledomain particle formation implies that the observation of coercivity does not require prior magnetic saturation under applied field, unlike the case of multidomain particles. In itself, it does not give any indication on the magnetization reversal process involved under Hm. 

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