Wall-Wall Interaction between Thin Magnetic Films

Abstract

Interactions between parallel Néel walls in sandwich‐type films were measured by transmission electron microscopy. A lower limit for the true interaction field was measured to be 3 Oe for two 100‐Å films of 80–17–3 Ni–Fe–Co separated by a 100‐Å layer of carbon. This experiment was limited by the coercive force of the two films. A locked‐in wall and domain configuration is described which prevented destruction of interacting walls. Escape fields in excess of 33 Oe (upper limit of the experimental apparatus) were measured for this type of structure. Based on the pair of linear dipoles model, the calculated escape field is 425 Oe. Other models, based on the interaction between linear dipoles and a uniformly distributed sheet‐of‐charge dipole, give similarly high escape fields. It is shown that the maximum interaction energy approaches the wall energy in magnitude, so that the effect on individual wall energies and widths resulting from the interaction of two walls should be included, although the effect of the interaction on the walls is shown to have a minor effect on calculated escape fields.