Fig. 4: Micromagnetic model simulations.

Configuration of the normalized magnetization vector m components in the system’s fully demagnetized state. Yellow (blue) indicates m_α = ±1. a m_x and (b) m_y for the case K_R = 0 and K_Z = 2K_U (i.e., no random anisotropy term): uniform anisotropy term dominates, and a standard domain configuration is achieved as expected. When the film properties are controlled by random anisotropy (c, d) the domain structure collapses and m continuously varies in random directions (depicted with white arrows). e For K_R comparable to the shape anisotropy (in this case, K_Z = 2K_R) localized vortexes with finite z-component appear, their position being highlighted in (c, d) by white dashed circles.