A theoretical and experimental study of 360°-walls in magnetically coupled bilayers

360°-walls in magnetic bilayers with a weak ferromagnetic coupling are calculated and analyzed microscopically. An important aspect of the calculations is the proper treatment of both local and nonlocal contributions to the stray field energy. The equilibrium zigzag angle of these walls is calculated, and found to agree with experimental observations. It is not obvious whether the observed walls consist of 360°-walls in both layers, or rather of 360°-0°-combinations. Conditions for separating the two cases in the microscope are derived from the calculations. Experiments are found to be in agreement with the computations if predominantly 360°-0°-pairs rather than 360°-360°-pairs are assumed to exist in reality