ENHANCED COERCIVITY DUE TO A LOCAL ANISOTROPY INCREASE

In most of the cases, a local wall energy decrease, usually associated with defects, leads to domain wall pinning. Another mechanism for coercivity is to create local maxima in the anisotropy energy. It is observed that in epitaxial garnet crystals, locally enhanced anisotropy due to stress arising from iridium inclusions embedded in the substrate is the source of coercivity. By modifying our previous energy barrier model, the coercivity has been calculated as a function of the size and position of the iridium inclusions in the substrate. It is shown that the coercivity varies nonlinearly with inclusion size and depth in the substrate material, in agreement with experimental observation.