Evolution of domain walls and reversal mechanism in exchange-coupled nanolayers

Abstract The demagnetization process for an exchange-coupled double-nanolayer system with perpendicular easy axes has been investigated within a micromagnetic model. The nucleation field, coercivity and angular distribution of the magnetization, have been obtained as functions of the thickness L of the misaligned layer, the layer with the easy axis perpendicular to the applied field. It is found that the coercivity is identical to the nucleation field only for very small L . For larger L (larger than a quarter of its Bloch wall width), the nucleation field is negative while the coercivity saturates at 0.414 H K , where H K is the anisotropy field. Thus for larger L , the coercivity mechanism is self-pinning rather than pure nucleation. This self-pinning has both attributes of traditional nucleation and pinning.