Influence of layer dependent perpendicular anisotropy on higher-order anisotropies in thin films

In this article the influence of a layer dependent second-order perpendicular anisotropy on higher-order anisotropies in thin films in the framework of a macrospin model is investigated. Second-order and fourth-order effective anisotropies are necessary to achieve a reasonable description of the micromagnetic results using the macrospin approximation. We found that the origin of the fourth-order anisotropy is linked to the layer-wise variation of magnetization direction in the structure leading to dependence on field strength and exchange stiffness. Our results show that the apparent fourth-order anisotropy increases with decrease in exchange stiffness and thereby decreasing exchange length. This observation has important implications for experimental investigations of the thickness dependence of the perpendicular anisotropy. •Layer wise variation of second-order perpendicular anisotropy on higher-order anisotropy is studied.•Origin of fourth-order anisotropy is found to be linked to the layer wise variation of magnetization direction.•Apparent fourth-order anisotropy varies with exchange stiffness and thereby exchange length.