Single domain and vortex state in ferromagnetic circular nanodots

In this article, we present an analytical approximation for calculating the magnetic energy in circular nanostructures for the vortex phase (closed magnetic flux) and the single domain phase. Comparing these energies in remanent state lead to a magnetic phase boundary between single domain phase and vortex phase, given by a critical thickness, which depends on the radius of the circular nanostructure. Experimental data and micromagnetic simulations have verified the analytical results. (C) 2002 American Institute of Physics.