STRONG STRIPES AS A PARADIGM OF QUASI-TOPOLOGICAL HYSTERESIS

Micromagnetic numerical computations are used to simulate the equilibrium magnetization distribution within (periodic) stripe patterns in thin films with a canted easy axis and intermediate quality factor. Two thicknesses are considered, either close to the critical thickness for domain nucleation in zero field or in fair excess of this last quantity. Several micromagnetic structural transitions are observed to take place under the action of an external field applied along the stripe's elongation direction. The computed intrinsic hysteresis curves prove to be in excellent agreement with experimental data, provided some degree of heterogeneous nucleation is accounted for. Although all computed equilibrium structures are homotopic to a point, transient magnetization distributions are shown to be just filling the order parameter space. For this reason, the transitions and the intrinsic hysteresis phenomena are termed quasi-topological.