Abstract
A free boundary domain wall pinning model for the magnetization reversal in magnetic thin films was proposed based on the experimental observations. The dependence of the switching field on the defect width, the direction of the external magnetic field, and the magnetic parameters (including magnetization, anisotropy, and exchange stiffness) of the host material and the defect was studied. In particular, the switching field, domain wall angle, and even the whole hysteresis loops of the strongly exchange-coupled NiFe/SmFe/NiFe trilayered film, which were found experimentally to depend on the direction of the external magnetic field, were well reconstructed by the free boundary domain wall pinning model using the experimental average magnetic parameters of the film.