Easy axis orientation dependence of the micromagnetic properties of CrO₂ nanodiscs

Micromagnetic simulations were performed on seven isolated CrO₂ discs, each having different orientations of easy axis of magnetization (EAM), but, same 100 nm diameter and 50 nm thickness. The simulation results showed that for an external magnetic field applied along the x-axis, there was no emergence of vortex states corresponding to the relative orientations of the easy axis along [1 0 0], [1 1 0], [1 0 1] and [1 1 1]. Whereas, magnetic vortex states emerged for the relative orientations of the easy axis along [0 1 0], [0 0 1] and [0 1 1]. In another words, for the external field applied along the x-axis, if the relative orientation of the EAM is at θ = 0° or any proximity of 45° (i.e., 0° ≥ θ ≤ 55°), the vortex states did not emerge; but, for any orthogonal orientations (θ = 90°), magnetic vortex states emerged. For the easy axis orientation along [0 1 0] and [0 1 1], out-of-plane vortex states with its core magnetization pointing along the normal to the plane of the disc emerged. However, for the easy axis orientation along [0 0 1], in-plane magnetic vortex states emerged, with its core pointing along the applied magnetic field direction. Further, depending on the relative orientation of the applied magnetic field and its strength, various other magnetization configurations, such as C, S and O states, were obtained in the simulations. (author)