From nucleation to coercivity

Abstract

The demagnetization process of an exchange-coupled hard/soft/hard magnetic system and its coercivity mechanism are investigated within a micromagnetic framework. The calculation reveals that the demagnetization is a three-step process: (i) it begins with the nucleation of a transition region, (ii) the subsequent evolution of the domain wall near the interface, and (iii) the irreversible domain-wall motion from the soft phase into hard phase. As the thickness of the soft interlayer decreases, the dominant mechanism of coercivity switches from pinning to nucleation. However, for very thin interlayer, the three-step process occurs at the same applied field. © 2005 American Institute of Physics.