360 deg. domain wall generation in the soft layer of magnetic tunnel junctions

High spatial resolution x-ray photoemission electron microscopy technique has been used to study the influence of the dipolar coupling taking place between the NiFe and the Co ferromagnetic electrodes of micron sized, elliptical shaped magnetic tunnel junctions. The chemical selectivity of this technique allows us to observe independently the magnetic domain structure in each ferromagnetic electrode. The combination of this powerful imaging technique with micromagnetic simulations allows us to evidence that a 360 deg. domain wall can be stabilized in the NiFe soft layer. In this letter, we discuss the origin and the formation conditions of those 360 deg. domain walls evidenced experimentally and numerically