Geometry-dependent head-to-head domain wall phase diagram and domain wall widths in ferromagnetic ring structures

Systematical investigation of more than 40 different geometries of Co and Py rings are made and phase transitions between different domain wall types as a function of the geometrical parameters is determined. In phase diagrams, the critical parameters where the transitions occur are directly correlated with the energy terms that govern the domain wall type (exchange energy vs. stray field energy). Comparison with theoretical calculations and micromagnetic simulations reveal the importance of local energy minima, and the geometry-dependent height of the energy barriers can be derived.