Shape dependence of the switching field in small structures

For small structures, the switching behaviour is controlled by the edge domains. In one scenario, the edge domains move inside the sample and annihilate each other. We show by results from Monte Carlo simulation that the energy change consists of a domain wall bending energy and a dipolar contribution which now is two dimensional. As a result the switching field is not a simple function of the aspect ratio alone. This differs from the bulk shape anisotropy effect which is mainly from the dipolar contribution.