Micromagnetic study of magnetic configurations in submicron permalloy disks

We report a finite-element study of magnetic configurations in submicron permalloy disks using micromagnetics principles. Depending on the disk size, many (meta)stable magnetic states such as normal and twisted onion, in-plane vortex, and various buckle states are observed. A diagram is constructed to bring out the dependence of the different remanent states on the disk diameter and thickness. It shows that the disk thickness is the decisive factor in determining whether a vortex state is energetically more favorable than an onion state, and that the disk diameter determines whether some in-plane buckling can be sustainable.