Mechanism for domain expansion in MAMMOS

A magnetic amplifying magnetooptical system (MAMMOS) model was created which calculates the size of the expanded domains in the readout layer by computing the forces on the domain wall. Using the model, the ratio of nucleation coercivity to domain wall motion coercivity, H_c,n/H_c,m, was found to be an important factor governing the final expanded domain size in MAMMOS. Simulation results indicated that H_c,n/H_c,m>5 is needed for a good readout signal. Experiments measuring the nucleation coercivity in localized areas on a MAMMOS readout layer agree with the modeling results. In the experiments, a wafer was patterned with islands of magnetic material and the switching behavior was measured. For a MAMMOS film, the ratio of H_c,n/H_c,m was measured to be 13 on average in a 400 μm² area.