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We present overdamped micromagnetic simulations of the time evolution of magnetic droplet solitons which are formed in a thin film with perpendicular magnetic anisotropy by injecting a spin polarized current through a circular nanocontact. The overdamped dynamics help explore the effective energy landscape of these structures and permit identification of stationary states that are either energy extrema or saddle configurations. Our micromagnetic simulations start with configurations that are numerical solutions of a one-dimensional model where the magnetization depends only on the radial distance to the center of the nanocontact. We verify that these solutions correspond either to energy minima or saddle states, and use them to estimate thermal activation barriers for various current strengths. From the two-dimensional micromagnetic simulations, we identify a new persistent state which does not appear in the one-dimensional model. [ABSTRACT FROM AUTHOR]

Numerical simulations were performed for thin ferromagnetic nanorings with non-negligible anisotropy. In a thin film, the cubic crystalline anisotropy reduces to a four-fold symmetric term favoring magnetization along the \pm\mathhat\bf x and \pm\mathhat\bf y directions. Our numerical studies use an extension of the previously proposed algorithm for thin film micromagnetic simulations based on optimal grids for the calculation of the stray field. The relative strength of the magnetostatic energy was varied with respect to the crystalline and exchange energies. The remanent magnetization configurations were obtained for a variety of ring geometries and initial saturation orientations. The magnetocrystalline contribution causes the appearance of distinct domains in the annular structure, resulting in a new variety of magnetization configurations. Based on energetic considerations we provide a classification of possible remanent states. [ABSTRACT FROM AUTHOR]