2D WALL PROFILES IN EXCHANGE-COUPLED BILAYERS

Two-dimensional wall configurations in exchange coupled bilayers are c alculated using numerical micromagnetic simulations. Starting with a 1 80-degrees domain arrangement in zero field, full saturation is, under bard axis field, only reached for field values large with respect to the anisotropy field, due to the nucleation of 360-degrees walls. Thei r collapse field is computed versus the magnitude of the interlayer ex change coupling. A novel hysteresis mechanism, specific of large coupl ing constants and involving superposed 360-degrees walls is described.